What is the correct way of saying this:

  • I have completed three years of a six years course.
  • I have completed three years of a six-years course?

And also, should it be 'six year' or 'six years' here?

  • 2
    "A six-year course". Measure expressions like this have a singular noun base, hence "year", not "years". As Andrew Leach says in his answer, six-year" is a compound adjective, a single word, and hence should be hyphenated.
    – BillJ
    Commented Dec 30, 2018 at 11:08

2 Answers 2


John Lawler calls this the eleven-year-old boy rule.

When a noun modifier consists of more than one word, it goes after the noun it modifies.
When a noun modifier consists of only one word, it goes before the noun it modifies.

Mnemonic: an eleven-year-old boy versus a boy eleven years old

A single word (which includes a hyphenated word, as here) is an adjective; a multi-word phrase is an adjectival phrase. Adjectives are not inflected for number, and will always be singular — hence "eleven-year". It doesn't matter whether you are talking about a seven-year itch or an eleven-year-old boy, it's always year before the noun. You might get an itch every seven years, where the adjectival phrase does have a plural.

In your example, six-year is a single adjective going before the noun it modifies. It should be hyphenated because it's a single word, and it should be singular because adjectives are always singular.

Note that whether the number is spelled out ("eleven") or presented in digits ("11"), everything else remains the same: year when before the main noun or years when after it; hyphenating before the noun and not hyphenated after it. The way the number is written is a matter of style and doesn't alter the rules about how the resultant single word or phrase is used.

  • 1
    I don't know whether I'd call it a single word. You're not going to find it in any dictionaries. And with things like under-the-radar, the spelling will change depending on whether it's an attribute or predicate adjective, which is a really weird property for a "word" to have. Commented Dec 30, 2018 at 11:50
  • I'm very happy for others to write a better answer. This question seems to be a good one to make the canonical dupe-target.
    – Andrew Leach
    Commented Dec 30, 2018 at 12:18
  • There are many who consider numbers neither adjectives nor determiners. Then again, 'six-year course' and 'six-year-old boy' are not isoformal. Commented Mar 13, 2021 at 18:36
  • "six-year" is not a single word. It's two words forming an adjective phrase, with a hyphen used to make it clear that six modifies "year" and not whatever noun this phrase is attached to.
    – andru
    Commented Jan 23, 2022 at 19:01
  • @andru The number of words in 'six-year' depends on how one chooses to define 'word'. Should the spelling variants 'inkwell' and 'ink well' be classed differently ... both are essentially the same compound noun. More important is the number of lexemes (after Crystal, units of meaning) ... and I'm struggling here. [number] + [unit] ... or [measure]? Commented Sep 13, 2023 at 9:59

The correct answer is this:

I have completed three years of a six-year course.

In this case, what you have is a compound noun. Compound nouns occur when you have one noun that describes another. Example: military campaign, job hunt, standing desk chair 5-year old.

When to use a hyphen:

You use the hyphen whenever there are numbers before the noun. Consider this:

  1. This girl is 6 years old and she hit her older brother.
  2. This 6-year-old girl hit her older brother.

Even when the noun is not descriptive, the numbers are combined.

  • A 5-yead-old could do this.

Mistakes to avoid:

When forming a compound noun only the head noun (the final word) is given the plural "s". Example: Military campaigns (only campaigns takes the s) Cosmetics courses (in this case Cosmetics is always plural) Job seekers (only seekers takes an s)

I have completed three years of a six-years course?

In your example, "six-years" should not have an s

  • I'm pretty sure that not all adjunct + head-noun strings can be regarded as compounds rather than collocations etc (One fine January morning ...). Commented Feb 1, 2021 at 15:08

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