easy english question...........

what is the difference between 「eight-year-old boy」and 「eight years old boy」?

The two phrase have the same meaning.

From Wikipedia
Hyphenation is also common with adjective-noun compound modifiers but, arguably, less generally. Where the adjective-noun phrase would be plural standing alone, it usually becomes singular and hyphenated when modifying another noun. For example, four days becomes four-day week.

Similarly, for 「eight-year-old boy」, we do not need to put a (s) after the word (year).
However, for 「eight years old boy」, we need to put a (s) after the word (year).

I hope I can help you.

:eight-year-old boy and eight years old boy diffrent is:

eight-year-old boy didn't got a [s], eight years old boy got [s].




{I can help you if you need help}