Question: I know sometimes adjectives need to be hyphenated before nouns, but there are plenty of times when I would expect a hyphen and don’t see one. Are there rules to help sort things out?
Answer: Great question. There are a lot of rules dealing with hyphens, so let’s focus specifically on compound adjectives, shall we?
The big thing we’ll be talking about is the compound adjective. If you have two or more words modifying a noun, and acting as a single idea, then hyphenate them. Some examples: run-of-the-mill day; pay-to-play politics; eat-or-be-eaten job market; etc.
Not all compound adjectives are expressions like those above. “Long-term” is a common one. Things like “low-risk” or “high-tolerance” are also compound adjectives. In these examples, the first adjective modifies the second adjective, and the entire adjective phrase modifies a noun (ex: low-risk investment).
Now that we’ve got that down: When don’t you use a hyphen? The big one is when your compound adjective phrase includes an adverb ending in “-ly” (or “very”). For example, you would describe someone as a “well-known singer,” but not as a “highly-known singer.” There should be no hyphen after “highly,” since the “-ly” lets you know it’s functioning as an adjective.
That brings me around to the point of the hyphen: eliminating confusion about how words are functioning. Consider the difference between a “small furniture sale” and a “small-furniture sale.” The former won’t give you a lot of options for chairs. The latter will probably leave you disappointed if you’re not a mouse.
The general rule is: When in doubt, hyphenate (unless you’ve got an “-ly” word, or “very). Better to avoid confusion than be stingy with the hyphen.