Hyphens in Ages

Hyphens in Ages

Hyphens are often seen in age-related terms. For example:

• A twenty-one-year-old has been arrested.
(Here, "twenty-one-year-old" is a noun.)
• Two twenty-one-year-old boys have been arrested.
(Here, "twenty-one-year-old" is an adjective.)
• They were twenty-one years old.
(There is only a hyphen in this third example because "twenty-one" is how 21 is written in full.)

More about Hyphens in Ages

Hyphens are used in three types of age-related terms:

(1) The compound-noun form.

For example:

• A twenty-four-year-old won the lottery.

(2) The compound-adjective form.

For example:

• A twenty-four-year-old woman won the lottery.

(3) The predicate-adjective form.

For example:

• The lottery winner is twenty-four years old.

Ages As Compound Nouns

Here are some more examples of the compound-noun form:

• He is a two-year-old with attitude.
(This is a compound noun. (It is just like words like ice-axe or cooking-oil, which are also compound nouns.) The words in a compound noun are linked together to show they are a singular entity.)
• I look after three two-year-olds from 9 am to 11 am.
(As with most nouns, there is a plural version too.)

The compound-noun form stands alone. It does not modify the word that follows. Read more about compound nouns.

Ages As Compound Adjectives

Here are some more examples of the compound-adjective form:

• He is a two-year-old horse.
(This is a compound adjective. It is no different from an adjective like "two-page" in "two-page document.")
• I look after three two-year-old horses.
(As with most adjectives, it can modify something singular or plural.)

The compound-adjective form does not stand alone. It modifies the word that follows ("horse" and "horses" in these examples). Read more about compound adjectives.

Ages As Predicate Adjectives

Here are some more examples of the predicate-adjective form:

• Jason is two years old.
(The predicate-adjective form appears after a linking verb (here, "is") and after the noun it modifies (here, "Jason"). There is no need to use hyphens in the predicate adjective form.)
• Jason is twenty-two years old.
(This version contains a hyphen only because twenty-two is spelled with a hyphen under the rules for writing numbers in full.)

Read more about predicate adjectives.