Hyphenating Phrases

We use hyphens for several things in written English. One of them is when we use two or more words together as an adjective. We call this a compound adjective. Compound adjectives are a little tricky because sometimes you can use the same string of words, but they aren’t used as an adjective. For example:

They were separated for two and a half years.

It was a two-and-a-half-year separation.

Here’s another, from the same source. (This time he got it right. Look a little more than halfway down the article):

a seven-year-old girl

And my example of using the phrase correctly the other way:

The girl was seven years old.

Notice that the word “year” doesn’t have the “s” in the adjective uses. We don’t show plural in our adjectives in English.