A prefix is a small word element that is attached to a following word, for example in sub-Saharan and submarine, where sub- means ‘below’ or ‘under’. A hyphen is used with some prefixes in some cases.
The table below lists a number of prefixes common in university and research writing:
|Prefix||Without Hyphen||With Hyphen|
Most prefixes do not normally use a hyphen; however, they may do so in the cases discussed below.
When to use a hyphen with a prefix
To make a word easier to read
A hyphen can be used to make a word easier to read:
Where the prefix and root have the same letter
To avoid a confusing combination of letters
Before a capital letter
With an abbreviation
With a date
To avoid ambiguity
to reform the United Nations
to re-form the United Nations
Most compounds with self- are written with a hyphen:
Non is somewhat of an exception, as both forms with and without a hyphen are found:
|Without Hyphen||With Hyphen|
US English tends to use non without a hyphen (apart from cases such as non-nuclear where the following word begins with n). In British English, both styles are used.
In your text, you should decide whether to use non with or without a hyphen, following the style of your target publication or a single dictionary as your guide.
Note: your word processor may not distinguish systematically between non spellings with and without a hyphen.