PC, Common Celtic
Reconstruction ofCeltic languages
RegionCentral or Western Europe
Eraca. 1300–800 BC

Proto-Celtic, or Common Celtic, is the hypothetical ancestral proto-language of all known Celtic languages, and a descendant of Proto-Indo-European. It is not attested in writing but has been partly reconstructed through the comparative method. Proto-Celtic is generally thought to have been spoken between 1300 and 800 BC, after which it began to split into different languages. Proto-Celtic is often associated with the Urnfield culture and particularly with the Hallstatt culture. Celtic languages share common features with Italic languages that are not found in other branches of Indo-European, suggesting the possibility of an earlier Italo-Celtic linguistic unity.

Proto-Celtic is currently being reconstructed through the comparative method by relying on later Celtic languages. Though Continental Celtic presents much substantiation for Proto-Celtic phonology, and some for its morphology, recorded material is too scanty to allow a secure reconstruction of syntax, though some complete sentences are recorded in the Continental Gaulish and Celtiberian. So the main sources for reconstruction come from Insular Celtic languages with the oldest literature found in Old Irish[1] and Middle Welsh,[2] dating back to authors flourishing in the 6th century AD.


Proto-Celtic is usually dated to the Late Bronze Age, ca. 1200–900 BC.[3] The fact that it is possible to reconstruct a Proto-Celtic word for 'iron' (traditionally reconstructed as *īsarnom) has long been taken as an indication that the divergence into individual Celtic languages did not start until the Iron Age (8th century BCE to 1st century BCE); otherwise, descendant languages would have developed their own, unrelated words for their metal. However, Schumacher[4] and Schrijver[5] suggest a date for Proto-Celtic as early as the 13th century BC, the time of the Canegrate culture, in northwest Italy, and the Urnfield culture in Central Europe, implying that the divergence may have already started in the Bronze Age.[why?]

Sound changes from Proto-Indo-European

The phonological changes from Proto-Indo-European (PIE) to Proto-Celtic (PC) may be summarized as follows.[6] The changes are roughly in chronological order, with changes that operate on the outcome of earlier ones appearing later in the list.

Late PIE

These changes are shared by several other Indo-European branches.


The following sound changes are shared with the Italic languages in particular, and are cited in support of the Italo-Celtic hypothesis.[7]

One change shows non-exact parallels in Italic: vocalization of syllabic resonants next to laryngeals depending on the environment. Similar developments appear in Italic, but for the syllabic nasals *m̩, *n̩, the result is Proto-Italic *əm, *ən (> Latin em ~ im, en ~ in).

Early PC

Late PC


PIE PC Example
PIE Proto-Celtic Old Irish Welsh
*p *ɸ *ph₂tḗr *ɸatīr father athir edrydd cf. home (< *ɸatrijo-)
*t *t *tréyes *trīs three trí tri
*k, ḱ *k *kh₂n̥-e-
cét /kʲeːd/
* * *kʷetwores *kʷetwares four ceth(a)ir pedwar
*b *b *h₂ébōl *abalom apple uball afal
*d *d *derḱ- *derk- see derc eye drych sight
*g, ǵ *g *gleh₁i-
to glue
giun, gin
(he) sticks fast
* *b *gʷenh₂ *bena woman ben O.W. ben
* *b *bʰére- *ber-o- carry berid (he) carries adfer
to restore
to take
* *d *dʰeh₁i- *di-na- suck denait they suck dynu, denu
*gʰ, ǵʰ *g *gʰh₁bʰ-(e)y-
(he) takes
*gʷʰ * *gʷʰn̥- *gʷan-o- kill, wound gonaid (he) wounds, slays gwanu stab
*s *s *sen-o- *senos old sen hen
*m *m *méh₂tēr *mātīr mother máthir modryb cf. aunt
*n *n *h₂nép-ōt- *neɸūts nephew niad nai
*l *l *leyǵʰ- *lig-e/o- lick ligid (he) licks llyo, llyfu
*r *r *h₃rēǵ-s *rīgs king (gen. ríg) rhi
*j *j *h₂yuh₁n-ḱós *juwankos young óac ieuanc
*w *w *h₂wl̥h₁tí- *wlatis rulership flaith gwlad country
PIE PC Example
PIE PC Old Irish Welsh
*a, *h₂e *a *h₂ep-h₃ōn- *abū
acc. *abonen
river aub afon
*ā, *eh₂ *ā *bʰréh₂tēr *brātīr brother bráthir brawd
*e, h₁e *e *sen-o- *senos old sen hen
*H between
*a *ph₂tḗr *ɸatīr father athir edrydd cf. home
*ē, eh₁ *ī *weh₁-ro- *wīros true fír gwir
*o, Ho, h₃e *o *Hroth₂o- *rotos wheel roth rhod
*ō, eh₃ in final syllable *ū *h₂nép-ōt- *neɸūts nephew niæ nai
elsewhere *ā *deh₃no- *dāno- gift dán dawn
*i *i *gʷih₃-tu- *bitus world bith byd
*ī, iH *ī *rīmeh₂ *rīmā number rím rhif
*ai, h₂ei, eh₂i *ai *kaikos
empty, one-eyed
*(h₁)ei, ēi, eh₁i *ei *deywos *deiwos god día duw
*oi, ōi, h₃ei, eh₃i *oi *oynos *oinos one óen oín;
áen aín
*u before wa o *h₂yuh₁n-ḱós *juwankos >
young óac ieuanc
elsewhere *u *srutos *srutos stream sruth ffrwd
*ū, uH *ū *ruHneh₂ *rūnā mystery rún rhin
*au, h₂eu, eh₂u *au *tausos *tausos silent táue silence
*(h₁)eu, ēu, eh₁u;
*ou, ōu, h₃eu, eh₃u
*ou *tewteh₂
M.W. bu, biw
* before stops *li *pl̥th₂nós *ɸlitanos wide lethan llydan
before other
*al *kl̥h₁- *kaljākos rooster cailech
(Ogham gen. caliaci)
* before stops *ri *bʰr̩ti- *briti- act of bearing; mind breth, brith bryd
before other
*ar *mr̩wos *marwos dead marb marw
* *am *dm̩-nh₂- *damna- subdue M.Ir.
he ties,
* *an *h₃dn̥t- *dant tooth dét /dʲeːd/ dant
*l̩H before obstruents *la *h₂wlh₁tí- *wlatis lordship flaith gwlad country
before sonorants * *pl̩Hmeh₂ *ɸlāmā hand lám llaw
*r̩H before obstruents *ra *mr̩Htom *mratom betrayal mrath brad
before sonorants * *ǵr̩Hnom *grānom grain grán grawn
*m̩H (presumably with
same distribution
as above)
*am/mā *dm̩h₂-ye/o- *damje/o- to tame daimid
goddef endure, suffer
*n̩H *an/nā *ǵn̩h₃to- ? *gnātos known gnáth gnawd customary

Phonological reconstruction


The following consonants have been reconstructed for Proto-Celtic (PC):

Manner Voicing  Bilabial   Alveolar   Palatal   Velar 
plain labialized
Plosive voiceless t k
voiced b d ɡ ɡʷ
Fricative ɸ s x
Nasal m n
Approximant l j w
Trill r

Allophones of plosives

Eska has recently proposed that PC stops allophonically manifest similarly to those in English. Voiceless stop phonemes /t k/ were aspirated word-initially except when preceded by /s/, hence aspirate allophones [tʰ kʰ]. And unaspirated voiced stops /b d ɡ/ were devoiced to [p t k] word-initially.[14][15]

This allophony may be reconstructed to PC from the following evidence:[14][15]

Evolution of plosives

Proto-Indo-European (PIE) voiced aspirate stops *, *, *gʰ/ǵʰ, merge with *b, *d, *g/ǵ in PC. The voiced aspirate labiovelar *gʷʰ did not merge with *, though: plain * became PC *b, while aspirated *gʷʰ became *. Thus, PIE *gʷen- 'woman' became Old Irish and Old Welsh ben, but PIE *gʷʰn̥- 'to kill, wound' became Old Irish gonaid and Welsh gwanu.

PIE *p is lost in PC, apparently going through the stages *ɸ (possibly a stage *[pʰ])[14] and *h (perhaps seen in the name Hercynia if this is of Celtic origin) before being completely lost word-initially and between vowels. Next to consonants, PC *ɸ underwent different changes: the clusters *ɸs and *ɸt became *xs and *xt respectively already in PC. PIE *sp- became Old Irish s (f- when lenited, exactly as for PIE *sw-) and Brythonic f; while Schrijver 1995, p. 348 argues there was an intermediate stage *sɸ- (in which *ɸ remained an independent phoneme until after Proto-Insular Celtic had diverged into Goidelic and Brythonic), McCone 1996, pp. 44–45 finds it more economical to believe that *sp- remained unchanged in PC, that is, the change *p to *ɸ did not happen when *s preceded. (Similarly, Grimm's law did not apply to *p, t, k after *s in Germanic, and the same exception occurred again in the High German consonant shift.)

Proto-Celtic Old Irish Welsh
*laɸs- > *laxs- 'shine' las-aid llach-ar
*seɸtam > *sextam 'seven' secht saith
*sɸeret- or *speret- 'heel' seir ffêr

In Gaulish and the Brittonic languages, the Proto-Indo-European * phoneme becomes a new *p sound. Thus, Gaulish petuar[ios], Welsh pedwar "four", but Old Irish cethair and Latin quattuor. Insofar as this new /p/ fills the gap in the phoneme inventory which was left by the disappearance of the equivalent stop in PIE, we may think of this as a chain shift.

The terms P-Celtic and Q-Celtic are useful for grouping Celtic languages based on the way they handle this one phoneme. But a simple division into P- / Q-Celtic may be untenable, as it does not do justice to the evidence of the ancient Continental Celtic languages. The many unusual shared innovations among the Insular Celtic languages are often also presented as evidence against a P- vs Q-Celtic division, but they may instead reflect a common substratum influence from the pre-Celtic languages of Britain and Ireland,[1], or simply continuing contact between the insular languages; in either case they would be irrelevant to the genetic classification of Celtic languages.

Q-Celtic languages may also have /p/ in loan words, though in early borrowings from Welsh into Primitive Irish, /kʷ/ was used by sound substitution due to a lack of a /p/ phoneme at the time:

Gaelic póg "kiss" was a later borrowing (from the second word of the Latin phrase osculum pacis "kiss of peace") at a stage where p was borrowed directly as p, without substituting c.


The PC vowel system is highly comparable to that reconstructed for PIE by Antoine Meillet. The following monophthongs are reconstructed:

Type Front Central Back
 long   short   long   short   long   short 
Close i   u
Mid e   o
Open   a  

The following diphthongs have also been reconstructed:

Type With -i With -u
With a- ai au
With o- oi ou



The morphological (structure) of nouns and adjectives demonstrates no arresting alterations from the parent language. Proto-Celtic is believed to have had nouns in three genders, three numbers and five to eight cases. The genders were masculine, feminine and neuter; the numbers were singular, plural and dual. The number of cases is a subject of contention:[16] while Old Irish may have only five, the evidence from Continental Celtic is considered[by whom?] rather unambiguous despite appeals to archaic retentions or morphological leveling. These cases were nominative, vocative, accusative, dative, genitive, ablative, locative and instrumental.

Nouns fall into nine or so declensions, depending on stem. There are *o-stems, *ā-stems, *i-stems, *u-stems, dental stems, velar stems, nasal stems, *r-stems and *s-stems.

*o-stem nouns

Case Singular Dual Plural
Nominative *makkʷos *makkʷou *makkʷoi
Vocative *makkʷe *makkʷou *makkʷūs
Accusative *makkʷom *makkʷou *makkʷūs
Genitive *makkʷī *makkʷūs *makkʷom
Dative *makkʷūi *makkʷobom *makkʷobos
Ablative *makkʷū *makkʷobim *makkʷobis
Instrumental *makkʷū *makkʷobim *makkʷūs
Locative *makkʷei *makkʷou *makkʷobis

However, Celtiberian shows -o- stem genitives ending in -o rather than : aualo "[son] of Avalos".[17]

Case Singular Dual Plural
Nominative *dūnom *dūnou *dūnā
Vocative *dūnom *dūnou *dūnā
Accusative *dūnom *dūnou *dūnā
Genitive *dūnī *dūnūs *dūnom
Dative *dūnūi *dūnobom *dūnobos
Ablative *dūnū *dūnobim *dūnobis
Instrumental *dūnū *dūnobim *dūnūs
Locative *dūnei *dūnou *dūnobis

*ā-stem nouns

E.g. *ɸlāmā 'hand' (feminine) (Old Irish lám; Welsh llaw, Cornish leuv, Old Breton lom)

Case Singular Dual Plural
Nominative *ɸlāmā *ɸlāmai *ɸlāmās
Vocative *ɸlāmā *ɸlāmai *ɸlāmās
Accusative *ɸlāmām *ɸlāmai *ɸlāmās
Genitive *ɸlāmās *ɸlāmajous *ɸlāmom
Dative *ɸlāmāi *ɸlāmābom *ɸlāmābos
Ablative *ɸlāmī *ɸlāmābim *ɸlāmābis
Instrumental *ɸlāmī *ɸlāmābim *ɸlāmābis
Locative *ɸlāmāi *ɸlāmābim *ɸlāmābis


E.g. *sūlis 'sight, view, eye' (feminine) (Brittonic sulis ~ Old Irish súil)

Case Singular Dual Plural
Nominative *sūlis *sūlī *sūlīs
Vocative *sūli *sūlī *sūlīs
Accusative *sūlim *sūlī *sūlīs
Genitive *sūleis *sūljous *sūljom
Dative *sūlei *sūlibom *sūlibos
Ablative *sūlī *sūlibim *sūlibis
Instrumental *sūlī *sūlibim *sūlibis
Locative *sūlī *sūlibim *sūlibis

E.g. *mori 'body of water, sea' (neuter) (Gaulish Mori- ~ Old Irish muir ~ Welsh môr)

Case Singular Dual Plural
Nominative *mori *morī *moryā
Vocative *mori *morī *moryā
Accusative *mori *morī *moryā
Genitive *moreis *moryous *moryom
Dative *morei *moribom *moribos
Ablative *morī *moribim *moribis
Instrumental *morī *moribim *moribis
Locative *morī *moribim *moribis

*u-stem nouns

E.g. *bitus 'world, existence' (masculine) (Gaulish Bitu- ~ Old Irish bith ~ Welsh byd ~ Breton bed)

Case Singular Dual Plural
Nominative *bitus *bitou *bitowes
Vocative *bitu *bitou *bitowes
Accusative *bitum *bitou *bitūs
Genitive *bitous *bitowou *bitowom
Dative *bitou *bitubom *bitubos
Ablative *bitū *bitubim *bitubis
Instrumental *bitū *bitubim *bitubis
Locative *bitū *bitubim *bitubis

E.g. *beru "rotisserie spit" (neuter)

Case Singular Dual Plural
Nominative *beru *berou *berwā
Vocative *beru *berou *berwā
Accusative *beru *berou *berwā
Genitive *berous *berowou *berowom
Dative *berou *berubom *berubos
Ablative *berū *berubim *berubis
Instrumental *berū *berubim *berubis
Locative *berū *berubim *berubis

Velar and dental stems

Before the *-s of the nominative singular, a velar consonant was fricated to *-x : *rīg- "king" > *rīxs. Likewise, final *-d devoiced to *-t-: *druwid- "druid" > *druwits.[18]

E.g. *rīxs "king" (masculine)

Case Singular Dual Plural
Nominative *rīxs *rīge *rīges
Vocative *rīxs *rīge *rīges
Accusative *rīgam *rīge *rīgās
Genitive *rīgos *rīgou *rīgom
Dative *rīgei *rīgobom *rīgobos
Ablative *rīgī *rīgobim *rīgobis
Instrumental *rīge *rīgobim *rīgobis
Locative *rīgi *rīgobim *rīgobis

E.g. *druwits "druid" (masculine)

Case Singular Dual Plural
Nominative *druwits *druwide *druwides
Vocative *druwits *druwide *druwides
Accusative *druwidem *druwide *druwidās
Genitive *druwidos *druwidou *druwidom
Dative *druwidei *druwidobom *druwidobos
Ablative *druwidī *druwidobim *druwidobis
Instrumental *druwide *druwidobim *druwidobis
Locative *druwidi *druwidobim *druwidobis

E.g. *karants "friend" (masculine)

Case Singular Dual Plural
Nominative *karants *karante *karantes
Vocative *karants *karante *karantes
Accusative *karantam *karante *karantās
Genitive *karantos *karantou *karantom
Dative *karantei *karantobom *karantobos
Ablative *karantī *karantobim *karantobis
Instrumental *karante *karantobim *karantobis
Locative *karanti *karantobim *karantobis

Nasal stems

Generally, nasal stems end in *-on-; this becomes *-ū in the nominative singular: *abon- "river" > *abū.

E.g. *abū "river" (feminine)

Case Singular Dual Plural
Nominative *abū *abone *abones
Vocative *abū *abone *abones
Accusative *abonam *abone *abonās
Genitive *abonos *abonou *abonom
Dative *abonei *abnobom *abnobos
Ablative *abonī *abnobim *abnobis
Instrumental *abone *abnobim *abnobis
Locative *aboni *abnobim *abnobis

E.g. *anman "name" (neuter)

Case Singular Dual Plural
Nominative *anman *anmanī *anmanā
Vocative *anman *anmanī *anmanā
Accusative *anman *anmanī *anmanā
Genitive *anmēs *anmanou *anmanom
Dative *anmanei *anmambom *anmambos
Ablative *anmanī *anmambim *anmambis
Instrumental *anmane *anmambim *anmambis
Locative *anmani *anmambim *anmambis

*s-stem nouns

Generally,*s-stems contain an *-es-, which becomes *-os in the nominative singular: *teges- 'house' > *tegos.

E.g.*tegos "house" (neuter)

Case Singular Dual Plural
Nominative *tegos *tegese *tegesa
Vocative *tegos *tegese *tegesa
Accusative *tegos *tegese *tegesa
Genitive *tegesos *tegesou *tegesom
Dative *tegesi *tegesobom *tegesobos
Ablative *tegesī *tegesobim *tegesobis
Instrumental *tegese *tegesobim *tegesobis
Locative *tegesi *tegesobim *tegesobis

*r-stem nouns

E.g. *ɸatīr 'father' (masculine)

Case Singular Dual Plural
Nominative *ɸatīr *ɸatere *ɸateres
Vocative *ɸatīr *ɸatere *ɸateres
Accusative *ɸateram *ɸatere *ɸaterās
Genitive *ɸatros *ɸatrou *ɸatrom
Dative *ɸatrei *ɸatrebom *ɸatrebos
Ablative *ɸatrī *ɸatrebim *ɸatrebis
Instrumental *ɸatre *ɸatrebim *ɸatrebis
Locative *ɸatri *ɸatrebim *ɸatrebis

E.g. *mātīr 'mother' (feminine)

Case Singular Dual Plural
Nominative *mātīr *mātere *māteres
Vocative *mātīr *mātere *māteres
Accusative *māteram *mātere *māterās
Genitive *mātros *mātrou *mātrom
Dative *mātrei *mātrebom *mātrebos
Ablative *mātrī *mātrebim *mātrebis
Instrumental *mātre *mātrebim *mātrebis
Locative *mātri *mātrebim *mātrebis


The following personal pronouns in Celtic can be reconstructed as follows:[19]: 220–221 [20]: 281 

Case First-person Second-person
Singular Plural Singular Plural
Nominative * *snī * *swī
Accusative *me[* 1] *snos *tu *swes
Genitive *mene[* 2] ? *towe ?
  1. ^ Remade as *mu in the prehistory of Irish by analogy to *tu.
  2. ^ Remade as *mowe in the prehistory of Irish by analogy to *towe.

The following third-person pronouns in Proto-Celtic may also be reconstructed.[21]: 62 [19]: 220 

Case Singular Plural
Masculine Feminine Neuter
Nominative *es, *ēs * *ed *eyes
Accusative *em *seyam? *sīm? *sūs
Genitive *esyo *esyās *esyo *ēsom? *esom?
*e(s)yōi *esyāi *e(s)yōi *ēbis

Forms of the masculine singular relative pronoun *yo- can be found in the first Botorrita plaque: The form io-s in line 10 is the nominative singular masculine of the relative pronoun from Proto-Indo-European *yo- (Sanskrit ya-, Greek hos), which shows up in Old Irish only as the aspiration for leniting relative verb forms. Line 7 has the accusative singular io-m and the dative singular io-mui of the same root. [22]


Adjectives in Proto-Celtic had positive, comparative, superlative and equative degrees of comparison.[23]

Positive-degree inflection classes

Four inflection classes for positive-degree adjectives are known. Most adjectives belonged to the o-ā class, in which the adjectives inflected like masculine o-stems, neuter o-stems and feminine ā-stems when agreeing with nouns of their respective genders. A much smaller minority of adjectives were i- and u-stems.[23]

Consonant-stem adjectives also existed but were vanishingly rare, with only relics in Old Irish like "hot" < *teɸents.

Comparative degree

The comparative degree was formed on most adjectives by attaching *-yūs to the adjective stem. For instance, *senos "old" would have a comparative *senyūs "older". However, some Caland system adjectives instead had a comparative ending in *-is, which was then extended to *-ais. For example, *ɸlitanos "wide" had a comparative *ɸletais.[24]

Superlative degree

The superlative was formed by simply attaching *-isamos to the adjective stem. In some adjectives where the stem ends in *s, the suffix is truncated to *-(s)amos by haplology.[24] Thus, *senos "old" would have a superlative *senisamos "oldest" but *trexsnos (stem *trexs-) would have a superlative *trexsamos.


From comparison between early Old Irish and Gaulish forms it seems that Continental and Insular Celtic verbs developed differently and so the study of Irish and Welsh may have unduly weighted past opinion of Proto-Celtic verb morphology.[citation needed] It can be inferred from Gaulish and Celtiberian as well as Insular Celtic that the Proto-Celtic verb had at least three moods:

and four tenses:

A probable optative mood also features in Gaulish (tixsintor) and an infinitive (with a characteristic ending -unei) in Celtiberian.[25][26]

Verbs were formed by adding suffixes to a verbal stem. The stem might be thematic or athematic, an open or a closed syllable.

Primary endings

The primary endings in Proto-Celtic were as follows. They were used to form the present, future, and subjunctive conjugations.[19]

Proto-Celtic primary endings
Person and number Basic endings Thematic present
Active Mediopassive Active Mediopassive
1st sg. * (thematic)
*-mi (athematic)
*-ūr * *-ūr
2nd sg. *-si *-tar *-esi *-etar
3rd sg. *-ti *-tor *-eti *-etor
1st pl. *-mosi *-mor *-omosi *-omor
2nd pl. *-tesi *-dwe *-etesi *-edwe
3rd pl. *-nti *-ntor *-onti *-ontor

Nasal-infix presents

In Proto-Celtic, the Indo-European nasal infix presents split into two categories: ones originally derived from laryngeal-final roots (i.e. seṭ roots in Sanskrit), and ones that were not (i.e. from aniṭ roots). In seṭ verbs, the nasal appears at the end of the present stem, while in aniṭ-derived verbs the nasal was followed by a root-final stop (generally -g- in Old Irish).

To aniṭ roots

Aniṭ nasal infix verbs conjugated exactly like basic thematic verbs in the present tense.

However, the origin of the invariant root vowel in -o- in *CewC- roots in Old Irish is unclear. Usually, it is held that the consonantism in these verbs was generalized in favour of the plural stem *CunC- in Old Irish. One would expect alternation between o in the 1st- and 3rd- person plural and -u- elsewhere in the present; but for both contexts Old Irish only attests -o-.

The following verbs can be reconstructed in this class:

To seṭ roots

On the other hand, the seṭ presents originally had a long vowel after the nasal in the singular and -a- after the nasal in the plural, but the attested Celtic languages levelled this alternation away. Gaulish shows traces of the singular long-vowel vocalism while Old Irish generalized the plural -a- to the singular.[27]

The seṭ nasal-infix presents were further subdivided into subcategories based on the root-final laryngeal. Traditionally two subclasses have long been accepted, the *h₁ subclass (cited with a -ni- suffix) and *h₂ (cited with a -na- suffix). *h₃ nasal-infixed verbs were often leveled to act like *h₂ verbs, being also cited with a -na- suffix; the only original difference between the two would have been the 3rd-person plural ending in *-nonti instead of *-nanti.

The nasal-infix seṭ verbs in Proto-Celtic underwent multiple levelings. First, the suffixal vowel in the plural forms was harmonized so that they would all be the short counterpart to the vowel in the singular forms. Then all the long vowels in the singular were shortened to make the suffix vowel identical in quality and length across all person-number combinations.[28]: 11–23 

Evolution of Proto-Celtic ablaut in the nasal infix for seṭ roots
Person and number Pre-leveling Leveling of vowel quality Leveling of vowel length
*h₁ verbs *h₂ verbs *h₃ verbs *h₁ verbs *h₂ and *h₃ verbs *h₁ verbs *h₂ and *h₃ verbs
1st sg. *-nīmi *-nāmi *-nāmi *-nīmi *-nāmi *-nimi *-nami
2nd sg. *-nīsi *-nāsi *-nāsi *-nīsi *-nāsi *-nisi *-nasi
3rd sg. *-nīti *-nāti *-nāti *-nīti *-nāti *-niti *-nati
1st pl. *-namosi *-namosi *-namosi *-nimosi *-namosi *-nimosi *-namosi
2nd pl. *-natesi *-natesi *-natesi *-nitesi *-natesi *-nitesi *-natesi
3rd pl. *-nenti *-nanti *-nonti *-ninti *-nanti *-ninti *-nanti

Preterite formations

There were two or three major preterite formations in Proto-Celtic, plus another moribund type.

The s-, t-, and root aorist preterites take Indo-European secondary endings, while the reduplicated suffix preterite took stative endings. These endings are:[29]: 62–67 

Proto-Celtic preterite endings
Person and number Ending type
Secondary endings Stative endings
1st sg. *-am *-a
2nd sg. *-s *-as
3rd sg. *-t *-e
1st pl. *-mo(s) *-mo
2nd pl. *-te(s) *-te
3rd pl. *-ant *-ar

The Old Irish t-preterite was traditionally assumed to be a divergent evolution from the s-preterite, but that derivation was challenged by Jay Jasanoff, who alleges that they were instead imperfects of Narten presents. Either derivation requires Narten ablaut anyway, leading to a stem vowel i in the singular and e in the plural. The stem vowel in the t-preterite was leveled to *e if the next consonant was either velar or *m, and *i in front of *r or *l.[30]

Suffixless preterites

Many suffixless preterite formations featured reduplication. The nature of the reduplication depends on the structure of the root.[29]: 68–79 

Proto-Celtic suffixless preterites
Root Meaning Shape Preterite stem Notes
*keng- "to step" Other root types *ke-kong- Classic Indo-European reduplication, where the root is put in the o-grade and the prefixed reduplicant is formed with the first consonant followed by *e.
*nigʷ- "to wash" *C(R)eiT- *ni-noig- In Proto-Celtic, roots with a semivowel (PIE *-y- or *-w-) before a non-laryngeal consonant have the reduplicant formed not with the first consonant of the root followed by *e, but instead the first consonant of the root followed by the semivowel. The root itself remains in the o-grade.
*duk- "to lead, carry" *C(R)euT- *du-douk-
*gʷed- "to pray" *CeT- *gʷād- Roots ending in only a single stop as their coda generally merely change the stem vowel to *ā to form their preterite, without apparent reduplication. It originally spread from *ād- (from *h₁e-h₁od-), the preterite stem for *ed- "to eat".
*kerd- "to throw, put" *CeRT- *kard- A few roots in *CeRT- also had the *CeT- preterite formation applied to them but the long *ā was shortened due to Osthoff's law.
*dā- "to give" *C(C)eH- *de-dū (singular)
*ded(a)- (plural)
Laryngeal-final roots produced long vowels in the root syllable in the singular, but not in the plural (where the root was in the zero-grade instead). Usually the singular stem was generalized in Celtic, but in these cases the plural stem was generalized.
*kʷri- "to buy" *C(R)eiH- *kʷi-kʷr- The treatment for *CeH- roots was also extended to *C(R)eiH- roots. Due to the roots' semivowel, the reduplicant also contains the semivowel.

Future formations

One major formation of the future in Celtic, the s-future. It is a descendant of the Proto-Indo-European (h₁)se-desiderative, with i-reduplication in many verbs. The Old Irish a- and s-future come from here.[28]

Another future formation, attested only in Gaulish, is the -sye-desiderative.

Subjunctive formations

Most verbs took one subjunctive suffix in Proto-Celtic, -(a)s-, followed by the thematic primary endings. It was a descendant of the subjunctive of an Indo-European sigmatic thematic formation *-seti. The -ase- variant originated in roots that ended in a laryngeal in Proto-Indo-European; when the *-se- suffix was attached right after a laryngeal, the laryngeal regularly vocalized into *-a-. It would then analogically spread to other Celtic strong verb roots ending in sonorants in addition to the weak verbs, even if the root did not originally end in a laryngeal.[28]

There were also three verbs that did not use -(a)se-, instead straight-out taking thematised primary endings. Two of these verbs are *bwiyeti "to be, exist" (subjunctive *bweti) and *klinutor "to hear" (subjunctive *klowetor).[31]

Primary subjunctive formations in Proto-Celtic generally use the e-grade of the verb root, even if the present stem uses the zero-grade.

Imperative formation

Imperative endings in Proto-Celtic were as follows:[19]: 147–148 [23]

Imperative endings in Proto-Celtic
Person and number Active endings
Basic endings With thematic vowels
2nd sg. -∅, *-si *-e
3rd sg. *-tou, *-tūd, *-tu *-etou, *-etūd, *-etu
1st pl. *-mo(s) *-omo(s)
2nd pl. *-te(s) *-ete(s)
3rd pl. *-ntou, *-ntu *-ontou, *-ontu
Second-person singular imperative

The second-person singular imperative was generally endingless in the active; no ending was generally added to athematic verbs. On thematic -e/o- verbs, the imperative ended in thematic vowel *-e. However, there is also another second-person singular active imperative ending, -si, which was attached to the verb root athematically even with thematic strong verbs.[32]

The thematic deponent second-person singular imperative ending was *-eso. The -the in Old Irish is secondary.[33][19]: 140 

Third-person imperative

The third-person imperative endings in Insular Celtic, Gaulish and Celtiberian have completely separate origins from each other. The Insular Celtic endings are derived from *-tou, *-ntou, Gaulish endings from *-tu, *-ntu, and the Celtiberian third-person imperative singular ending stems from *-tūd.[23]

Example conjugations

Scholarly reconstructions [6][34][35][36] may be summarised in tabular format.[dubiousdiscuss]

Conjugation like *bere/o- 'bear, carry, flow'
Person Present Imperfect Future Past
Active Medio-
Active Medio-
Active Medio-
Active Medio-
Indicative 1st sg. *berū *berūr *beremam *bibrāsū *bibrāsūr *bīram
2nd sg. *beresi *beretar *beretās *bibrāsesi *bibrāsetar *birs
3rd sg. *bereti *beretor *bereto *bibrāseti *bibrāsetor *birt ?
1st pl. *beromosi *beromor *beremo *bibrāsomosi *bibrāsomor *berme
2nd pl. *beretesi *beredwe ? *bibrāsete *bibrāsedwe *berte
3rd pl. *beronti *berontor *berento *bibrāsonti *bibrāsontor *berant ?
Subjunctive 1st sg. *berasū *berasūr
2nd sg. *berasesi *berasetar
3rd sg. *beraseti *berasetor
1st pl. *berasomosi *berasomor
2nd pl. *berasetesi *berasedwe
3rd pl. *berasonti *berasontor
Imperative 2nd sg. *bere *bereso
3rd sg. *beretou ?
1st pl. *beromos ?
2nd pl. *berete ?
3rd pl. *berontou ?
Participle *beronts *beromnos *bertyos *britos


The copula *esti was irregular. It had both athematic and thematic conjugations in the present tense. Schrijver supposes that its athematic present was used clause-initially and the thematic conjugation was used when that was not the case.[37]

Conjugation of *esti in Proto-Celtic
Person Present
Athematic Thematic
1st sg. *esmi *esū
2nd sg. *esi *esesi
3rd sg. *esti *eseti
1st pl. *esmosi *esomosi
2nd pl. **estes *esetes
3rd pl. *senti **esonti


The vast majority of reliably reconstructible lexical items in Proto-Celtic have good Indo-European etymologies, unlike what is found in, for example, the Greek language--at least 90% according to Matasovic.[38] These include most of the items on the Swadesh list of basic vocabulary. But a few words that do not have Indo-European cognates, so may be borrowings from substrate or adstrate Pre-Indo-European languages, are also from basic vocabulary, including *bodyo- ‘yellow’ (though this has possible cognates in Italic), *kani "good," and *klukka "stone."[39] It is notable that fully 32 items have been reconstructed for Proto-Celtic with the meaning "fight."[40]

See also



  1. ^ Celtic literature at, accessed 7 February 2018
  2. ^ Rhys, John (1905). Evans, E. Vincent (ed.). "The Origin of the Welsh Englyn and Kindred Metres". Y Cymmrodor. XVIII. London: Honourable Society of Cymmrodorion.
  3. ^ Koch, John T. (2020). Celto-Germanic Later Prehistory and Post-Proto-Indo-European vocabulary in the North and West Archived 2021-11-25 at the Wayback Machine, pp. 45–48.
  4. ^ Schumacher, Stefan (2004). Die keltischen Primärverben. Ein vergleichendes, etymologisches und morphologisches Lexikon (in German). Innsbruck, Austria: Institut für Sprachen und Literaturen der Universität Innsbruck. p. 85. ISBN 3-85124-692-6.
  5. ^ Schrijver, Peter (2016). "17. Ancillary study: Sound Change, the Italo-Celtic Linguistic Unity, and the Italian Homeland of Celtic". In Koch, John T.; Cunliffe, Barry (eds.). Celtic from the West 3: Atlantic Europe in the Metal Ages – Questions of Shared Language. Oxford, UK: Oxbow Books. pp. 489–502. ISBN 978-1-78570-227-3. Retrieved May 12, 2019.
  6. ^ a b Matasović 2009.
  7. ^ Schrijver 2015, pp. 196–197.
  8. ^ Matasovic, R. (2009) Etymological Dictionary of Proto-Celtic. Brill. p.7
  9. ^ Salmon, Joseph (1992) Accentual Change and Language Contact Stanford UP
  10. ^ Matasovic, R. (2009) Etymological Dictionary of Proto-Celtic. Brill. pp.11–12
  11. ^ Cólera, Carlos Jordán (2007) "Celtiberian," e-Keltoi: Journal of Interdisciplinary Celtic Studies: Vol. 6, Article 17. p.759. Available at: accessed June 21, 2023
  12. ^ Welsh adfer 'to restore' < *ate-ber-, cymeryd < obsolete cymer < M.W. cymeraf < *kom-ber- (with -yd taken from the verbal noun cymryd < *kom-britu).
  13. ^ However, according to Hackstein (2002) *CH.CC > Ø in unstressed medial syllables. Thus, H can disappear in weak cases while being retained in strong cases, e.g. IE *dʰugh₂tḗr vs. *dʰugtr-os 'daughter' > early PC *dugater- ~ dugtr-. This then led to a paradigmatic split, resulting in Celtiberian tuateros, tuateres vs. Gaulish duxtir (< *dugtīr). (Zair 2012: 161, 163).
  14. ^ a b c Eska, Joseph F. (March 12, 2018). "Laryngeal Realism and the Prehistory of Celtic". Transactions of the Philological Society. 116 (3). Wiley: 320–331. doi:10.1111/1467-968x.12122. ISSN 0079-1636.
  15. ^ a b Eska, Joseph (January 26, 2021). "Laryngeal Realism and early Insular Celtic orthography". North American Journal of Celtic Studies. 3 (1): 1–17. ISSN 2472-7490. Retrieved November 24, 2021.
  16. ^ Pedersen, Holger (1913). Vergleichende Grammatik der keltischen Sprachen, 2. Band, Bedeutungslehre (Wortlehre). Göttingen: Vandenhoeck & Ruprecht. ISBN 978-3-525-26119-4.
  17. ^ Untermann, J. (1967). "Die Endung des Genitiv singularis der o-Stämme im Keltiberischen." In W. Meid (ed.), Beiträge zur Indogermanistik und Keltologie, Julius Pokorny zum 80. Geburtstag gewidmet, pp. 281–288. Innsbruck: Sprachwissenschaftliches Institut der Universität Innsbruck.
  18. ^ Stokes, Whitley (November 1887). "Celtic Declension". Transactions of the Philological Society. 20 (1): 97–201.
  19. ^ a b c d e McCone, Kim (2006). The Origins and Development of the Insular Celtic Verbal Complex. Maynooth studies in Celtic linguistics. Department of Old Irish, National University of Ireland. ISBN 978-0-901519-46-7.
  20. ^ Thurneysen, Rudolf (1940). A Grammar of Old Irish. Translated by Binchy, D. A; Bergin, Osborn. Dublin Institute for Advanced Studies. ISBN 1-85500-161-6.
  21. ^ Schrijver, Peter (1997). Studies in the History of Celtic Pronouns and Particles. Maynooth studies in Celtic linguistics. Department of Old Irish, National University of Ireland. ISBN 978-0-901519-59-7.
  22. ^ Matasovic, R. Etymological Dictionary of Proto-Celtic. Leiden: Brill. 2006. p. 436
  23. ^ a b c d Stüber, Karin. "The morphology of Celtic". In Jared Klein; Brian Joseph; Matthias Fritz (eds.). Handbook of Comparative and Historical Indo-European Linguistics. Vol. 2. De Gruyter Mouton. pp. 1203–1217.
  24. ^ a b Jasanoff, Jay (1991). "The origin of the Celtic comparative type OIr. tressa, MW trech 'stronger'". Die Sprache. 34: 171–189.
  25. ^ Stefan Schumacher, Die keltischen Primärverben: Ein vergleichendes, etymologisches und morphologisches Lexikon (Innsbruck: Institut für Sprachen und Literaturen der Universität, 2004).
  26. ^ Pierre-Yves Lambert, La langue gauloise: Description linguistique, commentaire d'inscriptions choisies (Paris: Errance, revised ed. 2003).
  27. ^ Lambert, Pierre-Yves; Stifter, David (2012). "Le plomb gaulois de Rezé". Études Celtiques (in French and English). 38 (1): 139–164. doi:10.3406/ecelt.2012.2351. ISSN 0373-1928.
  28. ^ a b c McCone, Kim (1991). The Indo-European Origins of the Old Irish Nasal Presents, Subjunctives and Futures. Innsbrucker Beiträge zur Sprachwissenschaft. IBS-Vertrieb. ISBN 978-3-85124-617-9.
  29. ^ a b Schumacher, Stefan; Schulze-Thulin, Britta; aan de Wiel, Caroline (2004). Die keltischen Primärverben. Ein vergleichendes, etymologisches und morphologisches Lexikon (in German). Innsbruck: Institut für Sprachen und Kulturen der Universität Innsbruck. ISBN 3-85124-692-6.
  30. ^ Jasanoff, Jay (2012). "Long-vowel preterites in Indo-European". In Melchert, Craig (ed.). The Indo-European Verb. Wiesbaden: Reichert Verlag. pp. 127–135.
  31. ^ Darling, Mark (2020). The Subjunctive in Celtic: Studies in Historical Phonology and Morphology (Thesis). University of Cambridge. doi:10.17863/CAM.57857. Retrieved September 1, 2022.
  32. ^ Jasanoff, Jay (1986). "Old Irish tair 'come!'". Transactions of the Philological Society. 84 (1). Wiley: 132–141. doi:10.1111/j.1467-968x.1986.tb01050.x. ISSN 0079-1636.
  33. ^ Barnes, Timothy (2015). "Old Irish cuire, its congeners, and the ending of the 2nd sg. middle imperative". Ériu. 65 (1): 49–56. doi:10.3318/eriu.2015.65.3. ISSN 2009-0056. Retrieved September 2, 2022.
  34. ^ Alexander MacBain, 1911, xxxvi–xxxvii; An etymological dictionary of the Gaelic language; Stirling: Eneas MacKay
  35. ^ Alan Ward, A Checklist of Proto-Celtic Lexical Items (1982, revised 1996), 7–14.
  36. ^ Examples of attested Gaulish verbs at
  37. ^ Schrijver, Peter (December 6, 2019). "Italo-Celtic and the Inflection of *es- 'be'". In Serangeli, Matilde; Olander, Thomas (eds.). Dispersals and Diversification. Brill. pp. 209–235. doi:10.1163/9789004416192_012. ISBN 9789004414501. S2CID 213806505.
  38. ^ Matasovic, R. (2009)Etymological Dictionary of Proto-Celtic Leiden: Brill. p. 443
  39. ^ Matasovic, R. (2009)Etymological Dictionary of Proto-Celtic Leiden: Brill. p. 443-444
  40. ^ English to Proto-Celtic Wordlist p. 44-45