Which of the following are correct and which are wrong?

  • The 2000-year-old computer
  • The 2000 year-old computer
  • The 2000 year old computer
  • The 2000-years-old computer
  • The 2000 years-old computer
  • The 2000 years old computer

In a documentary, BBC4 used the title The 2000 year-old computer, which I believe to be wrong. Am I right?

  • 2
    I would accept any of the first three.
    – GEdgar
    Jun 2, 2012 at 16:39
  • I'd go with GEdgar, although the second one looks strange because of the lonely hyphen.
    – Paola
    Jun 2, 2012 at 18:17
  • 1
    Hyphenation is a matter of individual taste and style, but modifiers that precede nouns don't get inflected for plural. Hence Shoes Store is a mistake, even though very few customers ever buy only one shoe. You can say a boy eleven years old or you can say an eleven year old boy (hyphens are inaudible in speech, so you can put them wherever you wish when you talk), but you can't say *an eleven years old boy or *a boy eleven year old. Jun 2, 2012 at 18:32

2 Answers 2


According to the Chicago manual of style...

When you hyphenate, it would be with hyphens between 2000 and year and old. So, 2000-year-old, but never 2000 year-old or 2000-year old. Now, to Paraphrase the CMOS for this example...

There is no need for hyphens in “2000 years old.” If you are using a phrase like that to modify another word or phrase, however, you need to bind it together with hyphens (a 2000-year-old grudge). Likewise, use a hyphen if “years old” comes before the noun it modifies (a years-old phobia over wearing the wrong earrings), but leave it open if it follows the noun (the moldy accretion on her cell phone was years old). Finally, you will need hyphens when the phrase is used as a noun (enough pizza for three 2000-year-olds).

So, taking that into account, a 2000-year-old computer would be correct. Or, if you were to rephrase, "a computer that was 2000 years old" would also be correct.

You are right. BBC4 was wrong.

  • 6
    The Chicago Manual of Style is interesting, but the BBC isn't 'wrong' just because it doesn't follow American advice. Jun 2, 2012 at 19:29
  • If BBC4 was wrong here, so is John Lawler (assuming he's not reconsidered over the intervening years). Jan 26, 2018 at 9:42

I'd say only the first one is correct.

A book called "English Grammar in Use" is British, and it would put hyphens on both sides of "year."

The last three are definitely unacceptable 'coz once a bunch of words precedes a Noun, they are no longer Nouns but an Adjective. And Adjectives can't become plural in English.


He's 6 yearS old. But... He's a 6-year-old boy.

It's 5 thousand dollarS. But... It's a 5-thousand-dollar bag.

It's 2 hours. But... It's a 2-hour-trip.

Similarly, we say "apple tree" but not "apples tree."

Personally, I believe this is also the reason why they're strung up together like that - to become just one unit describing the Noun (in this case, "computer").

  • 1
    Opps! Sorry. I missed this one: "He's a 6-YEAR-old boy" ;-)
    – Cool Elf
    Jun 2, 2012 at 20:15
  • 1
    Soon you'll be able to edit posts.
    – JLG
    Jun 2, 2012 at 20:42
  • I see. Thanks! I guess it has something to do wit the New User Restrictions? Coz I'm also required to type a minimum of 15 words to reply to you
    – Cool Elf
    Jun 3, 2012 at 7:07
  • 1
    Surely it’s a 2-hour trip, not a 2-hour-trip?
    – Timwi
    Jun 7, 2012 at 0:20
  • Hi Timwi. I've often seen it as 2-hour-trip
    – Cool Elf
    Jun 7, 2012 at 0:23

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