When do you need to use a hyphen for compound words? (6th edition)

In a temporary compound that is used as an adjective before a noun, use a hyphen if the term can be misread or if the term expresses a single thought (i.e., all words together modify the noun).

For example:

  • “the adolescents resided in two parent homes” means that two homes served as residences, whereas if the adolescents resided in “two-parent homes,” they each would live in a household headed by two parents.

A properly placed hyphen helps the reader understand the intended meaning.

Also use hyphens for

Compounds in which the base word is

  • capitalized: pro-Freudian
  • a number: post-1970
  • an abbreviation: pre-UCS trial
  • more than one word: non-achievement-oriented students

All “self-” compounds whether they are adjectives or nouns

  • self-report
  • self-esteem
  • the test was self-paced

Exception: self psychology

Words that could be misunderstood

  • re-pair [pair again]
  • re-form [form again]
  • un-ionized

Words in which the prefix ends and the base word begins with the same vowel

  • meta-analysis
  • anti-intellectual
  • co-occur