hyphens in prefixes

A prefix is a half word (e.g. anti- , ex- , post- , pre-) that is placed before a word to modify its meaning.

1. There is often confusion about when a hyphen should be used with a prefix. Unfortunately, there are no specific rules governing this, and a definitive list of the prefixed words acceptable without hyphens is yet to be compiled.

Examples:

Prehistoric

/ pre-historic

("Prehistoric" is so widely used that "pre-historic" is now considered wrong.)

ultraviolet

/ ultra-violet

(Most prefixed words exist in both forms.)

The attack would take place at night as the anti-government troops did not
possess infrared goggles.

(You can often choose when to use a hyphen in a prefixed word. In this example, the writer did not like the look of "antigovernment" or "infra-red" and so chose the versions above.)

GOOD NEWS

It is very likely that, in the beginning, all prefixed words had hyphens. However, over time, some hyphens in words have disappeared, whilst others have not. For most prefixed words, both versions exist (e.g. post-natal and postnatal). If you are unsure, use a hyphen. The hyphen version is very likely to be acceptable.

Other common prefixes are:

ante- (before)	ex- (former)	pre- (before)
anti- (against)	infra- (below)	pro- (for)
contra- (opposite to)	post- (after)	ultra- (above)

PREFIXES IN TITLES

When names or titles (with capital letters) are prefixed, the prefix is usually written with a lowercase letter and a hyphen.

I am aware that ex-Bishop Zoric, who was pro-Nazi, was still teaching in the
post-World War II era.

Associated lessons:

Alternatives to hyphens in compound adjectives
Hyphens in compound adjectives
Hyphens in compound nouns