Compound adjectives
In our experience, few aspects of style cause greater anxiety and raise more questions than compound adjectives.
When a compound adjective is shown hyphenated in the dictionary, you can assume only that the expression is hyphenated when it occurs directly before a noun. When the same combination of words falls elsewhere in the sentence, the use or omission of hyphens depends on how the words are used.
Basic Rules
A compound adjective consists of 2 or more words that function as a unit and express a single thought. These one-thought modifiers are derived from (and take the place of) adjective phrases and clauses.
In the process of becoming compound adjectives, the adjective phrases and clauses are usually reduced to a few essential words.
high-tech equipment (equipment that reflects a high level of technology)
a worst-case scenario (a scenario based on the worst outcome that could occur)
long-range treatment plan (a treatment plan projected over a long range of time)
EXCEPTIONS: A number of compounds are accepted as well-established compound nouns and easily grasped as a unit.
high school
real estate
When these expressions occur elsewhere in the sentence, drop the hyphen if the individual words no longer function as a compound adjective.
Before the Noun / Elsewhere in the sentence
a high-level decision / the decision must be made at a high level (object of a preposition)
an up-to-date diagnosis / please provide a diagnosis that is up to date (prepositional phrase)
an off-the-record comment / the next comment is off the record (prepositional phrase)
a no-nonsense attitude / we will tolerate no nonsense (object of a verb)
When these expressions occur elsewhere in the sentence but are in an inverted word order or altered form, retain the hyphen.
a tax-exempt status / the hospital's status is tax-exempt
government-funded initiative / initiative that is government-funded
The following kinds of compound adjectives almost always need to be hyphenated.
Noun + adjective (EXAMPLE: tax-exempt)
Noun + participle (EXAMPLE: government-owned)
Adjective + participle (EXAMPLE: friendly-looking)
Adjective + noun + ed (EXAMPLE: high-priced)
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