# Hyphens

### When do you need to use a hyphen for compound words?

### General Principle 1

If a compound adjective can be misread, use a hyphen.&#x20;

### General Principle 2

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

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

### General Principle 3

Most compound adjective rules are applicable only when the compound adjective precedes the term it modifies. If a compound adjective follows the term, do not use a hyphen, because relationships are sufficiently clear without one.

* client-centred counselling\
  **but**\
  the counselling was client centred
* _t_-test results\
  **but**\
  results from _t_ tests
* same-sex children\
  **but**\
  children of the same sex

### General Principle 4

Write most words formed with prefixes and suffixes as one word.

**Prefixes**

* aftereffect
* extracurricular
* multiphase
* socioeconomic

**Suffixes**

* agoraphobia
* wavelike
* cardiogram

### General Principle 5

When two or more compound modifiers have a common base, this base is sometimes omitted in all except the last modifier, but the hyphens are retained.

* Long- and short-term memory
* 2-, 3-, and 10-min trials
