The Definition: Two or more words are acting as a single modifier for a noun.
The Clue: They belong together. They are not part of a series that can separately describe the noun.
- I think Steve is a well-intentioned volunteer.
- Steve is a helpful, supportive volunteer.
- The 20-year-old man was too young to buy alcohol.
The Rule: If you can put “and” between the modifiers and it makes sense, it is not a compound modifier.
The Exception: If the modifier includes “very” or an “-ly” adverb, these words alone indicate that they are part of a compound modifier, so a hyphen is redundant.
- Most people think they have a well-developed sense of style.
- Steve has a highly developed sense of style.
- Susan has an open-minded view of the world.
- Doug thinks he has very liberal views.
The Kicker: Most compound modifiers are hyphenated when they follow the linking verb “to be.”
- I think his proposal is short-sighted.
The Caveat: But be careful to distinguish between a compound modifier and the same words not used as a modifier.
- His too-small effort couldn’t save the game.
- The coat he gave his mother was too small.