Year-Old-Years-Old | Commonly Confused Words

Year-old

/jɪər əʊld/

Used to describe someone or something's age in terms of years

My grandfather is a wise eighty-year-old.The nine-year-old impressed everyone with her talent.He adopted a three-year-old beagle at the shelter.

This word has no antonyms

/jɪrz oʊld/

Used to indicate the age of someone or something, showing the number of years they have existed.

She will turn eighteen years old next month.Puppies typically reach maturity at one year old.The ancient tree in the park is over 200 years old.

Use year-old when its part of a compound adjective describing a noun, like 7-year-old boy'.
Use years old when simply stating someones age, without more context, like I am 20 years old'.
Remember: year-old is hyphenated because it forms part of a larger phrase, whereas years old stands alone.
Year-old modifies a singular subject, while years old follows the subject as a predicate.
Think of year-old as attaching more directly to what it's describing.