Hyphen In Compound Expression With Noun And Past Participle

When a noun is put together with a past participle (a verb ending in ‑ed), this results in a compound adjective. Compound adjectives should always be hyphenated so the reader can distinguish them from the original, separate words. For instance, when we connect the noun community with the verb based, it makes the compound adjective community-based.

The municipal government is funding a community-based education system.

If there were no hyphen in this sentence, the reader might assume there was a word missing (maybe the author meant a community based on an education system?) The hyphen is required so that the past participle is changed from a verb to an adjective.

Wind-powered generators can be excellent sources of electricity.

Many veterinarians find meat-fed cats to be quite healthy.

Annie and Margaret are very close; they’re like long-lost sisters.

Knitting is my new-found activity of choice.

The history of America is fairly well-known around the world.