November 29

I walked a five kilometer long trail.

I walked a trail that was five kilometers long.

How come one needs to be plural and the other one doesn't? Is there a prescriptivist rule in English that describes this difference?

Also, is there a parallel to this rule in other languages? 731Butai (talk) 08:01, 29 November 2015 (UTC)[reply]

I've heard both of them either way, although your examples are more conventional for whatever reason. The subtlety seems to be whether it's being used as an adjective or in a descriptive phrase. As in, "It was a five kilometer trail" vs. "The trail was five kilometers long." ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:10, 29 November 2015 (UTC)[reply]

I parse these like "five kilometer long" in the first example are three attributives represented by a numeral, a noun and an adjective, while in the second example "long" is an adverbial modifier. As nouns in the attributive function are usually not pluralized, therefore the noun of the first example is not as well.--Lüboslóv Yęzýkin (talk) 10:49, 29 November 2015 (UTC)[reply]

The first example should be hyphenated: "I walked a five-kilometer-long trail." (See MOS:HYPHEN,sub-subsection 3, points 3 and 8.)

—Wavelength (talk) 14:31, 29 November 2015 (UTC)[reply]

Sure, if I was adding that sentence to a WP article. 731Butai (talk) 16:42, 29 November 2015 (UTC)[reply]

My Google search for hyphen measurements finds other style guides prescribing hyphenation in such expressions. For more than 12 months, I have been hyphenating attributive expressions of time measurement, as one can see by examining my contributions.

—Wavelength (talk) 17:29, 29 November 2015 (UTC)[reply]

I note that if one uses ((convert)) with |adj, the adjectival form includes a hyphen, eg

((convert|5|km|mi|adj=on)) trail → 5-kilometre (3.1 mi) trail.

However if you want to append "long", you have to include the hyphen yourself.

((convert|5|km|mi|adj=mid|long)) trail → 5-kilometre long (3.1 mi) trail

((convert|5|km|mi|adj=mid|-long)) trail → 5-kilometre-long (3.1 mi) trail

Mitch Ames (talk) 23:31, 29 November 2015 (UTC)[reply]

• Regarding the hyphen, note that it has to turn into a space if the expression includes an SI (metric) unit expressed as an abbreviation (officially called a symbol). It was a five-kilometer or five-kilometre trail, but it was a 5 km trail. That's because the use of SI symbols is governed by an international standard that applies regardless of which language is being used. Specifically, see section 5.3.3 of the standard, third paragraph:

Even when the value of a quantity is used as an adjective, a space is left between the numerical value and the unit symbol. Only when the name of the unit is spelled out would the ordinary rules of grammar apply, so that in English a hyphen would be used to separate the number from the unit.

The common British practice of writing 5km without a space is also in violation of the standard. (Note: I linked to the US edition of the standard because it's available online, but it specifically mentions what things in it are US-specific and this is not one of them.) --70.49.170.168 (talk) 09:33, 30 November 2015 (UTC)[reply]

• Expressions like "a ten foot pole" come from the Old English genitive plural form of "foot", fota which did not have a final /s/ or vowel mutation. (See ten foot pole here at Harvard.) In essence, the expression means a pole of ten feet. Since "ten foot" is not an adjective, hyphenating it is a solecism. μηδείς (talk) 18:45, 29 November 2015 (UTC)[reply]

I think that's exactly Wavelength's point, though. An adjective is required here. "A ten pole" and "a foot pole" make no sense, because neither "ten" nor "foot" is an adjective. "Ten foot" will not do either, as simply juxtaposing the two words does not convert them into one adjective. The alchemy comes with the hyphen: "ten-foot".

Back to the original question, and here are some more examples, not involving measurements: mouse plague, drug addict, pencil case, car rally, boot polish. Nobody would read these and believe the plague contained only one mouse, the addict used only one drug, the case accommodates only one pencil, the rally had only one car, or the polish is for shining only one boot. A car rally that contained 50 cars could be called "a 50-car rally", but "a 50 car rally" has no meaning, really. -- Jack of Oz ^{[pleasantries]} 20:07, 29 November 2015 (UTC)[reply]

Also, the singular is used even when the adjective is formed from a noun that is only ever used in the plural, such as "scissors" and "trousers".

Example: The main problem with his outfit was that one trouser-leg was longer than the other. It can't be "trouser leg", because there is no such word as "trouser"; that series of letters can exist only if an s is added to the end, or if it's hyphenated with "leg" or whatever. -- Jack of Oz ^{[pleasantries]} 20:59, 29 November 2015 (UTC)[reply]

I think I might need to press you on that one, Jack. Martinevans123 (talk) 23:03, 29 November 2015 (UTC)[reply]

Only if there were a style of car called a "50". Another example that comes to mind is "Rule Book", which for whatever sport it's for, certainly has more than one rule. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:01, 29 November 2015 (UTC)[reply]

Only if there were a style of car called a "50" - how does that compute? A rally of Ford cars would be a "Ford rally", not a "Ford-car rally". A rally of 30 Ford cars would be "a 30-car Ford rally". -- Jack of Oz ^{[pleasantries]} 22:49, 29 November 2015 (UTC)[reply]

Here is an example of singular "trouser" - "rear trouser pocket". ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:25, 30 November 2015 (UTC)[reply]

• In general, a "ten-foot pole" is wrong for the exact same reason that a 98.6-degree temperature is. The notion that only adjectives can modify nouns is simply false. The phrases John's dog, the dog that I saw yesterday, the dog on the corner are all perfectly cromulent.

We recently had the same issue where it was insisted that "combat sports history" should be hyphenated as combat-sports history, since "combat-sports" was supposedly being used as an adjective. But if it were being used as an adjective, then just as we could turn "black cat" or "brownish-black cat" into a cat that is black or a cat that is brownish-black, we would be able to turn "combat-sports history" into a history that is combat-sports.

And this is not just an exception because of the word history as if it were special; it's not. The terms "a socio-economical history" and a "marxist-leninist history" have absolutely no problem being turned into a history that is socio-economical or that is marxist-leninist. What we certainly do not do is turn a "500-page history" into a history that is 500-page.

Ergo, the assertion that "ten foot pole" is an adjectival phrase is wrong; it is a genitive one. And we most certainly cannot invent a "ten-foot pole" and then start taking about a pole that is ten-foot.

μηδείς (talk) 02:09, 30 November 2015 (UTC)[reply]

Imagine that English is some language from New Guinea with no written records before the 20th century. Will you then name "ten foot pole" a genetive phrase? No, it is not. "Ten foot" is not an adjective, neither it's a genetive, but it is an attributive represented by a numeral and a noun.--Lüboslóv Yęzýkin (talk) 08:14, 30 November 2015 (UTC)[reply]

That's very imaginative. Martinevans123 (talk) 09:40, 30 November 2015 (UTC)[reply]

It's called a synchronic approach.--Lüboslóv Yęzýkin (talk) 15:15, 30 November 2015 (UTC)[reply]

The purpose of hyphenation is to save readers time by making the garden-path parse the correct one, or in some cases to resolve an actual ambiguity (five-hundred-foot poles vs. five hundred-foot poles). I've never heard of a rule that "A-B C" should only be hyphenated if "C that is A-B" is also grammatical. -- BenRG (talk) 18:54, 30 November 2015 (UTC)[reply]

If one wants to argue, BenRG, that hyphens can be used to help the reader, that's entirely fine in my book. But in that case the choice of typography is entirely arbitrary. One could just as easily say "five hundred foot poles" vs. "five hundred foot poles", or a variety of other devices like five (5) hundred (100) vs. five hundred (500).

Ljuboslov is simply ignoring that I did give both a diachronic (historical) explanation, as well as a synchronic one. You can say a brownish-black cat is brownish-black. You cannot say a five hundred page book is five hundred page. Any fully competent native speaker is at least implicitly aware of this asymmetry. I suspect it was the nagging implicit knowledge that prompted Jack to ask for an explicit explanation of his original question. μηδείς (talk) 02:43, 1 December 2015 (UTC)[reply]

Since "ten foot" is not an adjective, hyphenating it is a solecism @Medeis: The following sources disagree with you:

• Chicago Manual of Style, 15th edition, p.303 (section 7.90, s.v. number, spelled out, + noun) a hundred-meter race, a 250-page book
• New Hart's Rules (2005) p.186 section 11.2.2. a six-foot wall

However, the latter (section 3.3. p.53) says noun+noun compounds used attributively are not hyphenated whereas adjective+noun compounds are (first-class seats vs labour market liberalization). jnestorius^(talk) 17:14, 5 December 2015 (UTC)[reply]