Filippo Salvatore Gilii (Spanish: Felipe Salvador Gilij) (1721–1789) was an Italian Jesuit priest who lived in the Province of Venezuela (in present day central Venezuela) on the Orinoco River. Gilii is a highly celebrated figure in early South American linguistics due to his advanced insights into the nature of languages. Gilii was born in Legogne, Italy (Umbria region). Most of what is known about the ethnology of the Tamanaco Indians was recorded by Gilii. One of his most notable works was Saggio di Storia Americana, o sia Storia Naturale, Civile, e Sacra De regni, e delle provincie Spagnuole di Terra-ferma nell' America meridionale, first published in four volumes in 1768. Commemorative stamp showing him were issued in 1998 by the Venezuelan government.
Gilii recognized sound correspondences (e.g. between /s/ : /tʃ/ : /ʃ/ in the Cariban family) and predated William Jones' third discourse suggesting genealogical relationships between languages. Unlike Jones, Gilii presented evidence in support of his hypothesis.
He also discussed major concepts of linguistics such as areal features between unrelated languages, loanwords (among American languages and from American languages into European languages), word order, language death, language origins, and nursery forms of child language (i.e. Lallwörter) discussed by Roman Jakobson.
Gilii found that the languages spoken in the Orinoco area belonged to nine "mother languages" (lenguas matrices), i.e. language families:
This classification is one of the earliest proposals of South American language families.
