General guidance on the use of prefixes

Prefix

Guidance

Example

anti-

Use a hyphen with:

  • letters;
  • names;
  • words beginning with 'i';
  • two-word compounds used as adjectives.

 

anti-HBs,
anti-Bitis-Echis-Naja serum,
anti-icteric,
anti-gas gangrene serum

co-

A hyphen can be used as an aid to reading if the following word starts with a vowel. Do not insert a hyphen into well-established words. See examples.

co-ordinate, co-author, co-exist, co-intervention

comorbidity, coincidence, coalesce, coercion

inter-

Use a hyphen for compounds that are not used commonly. Otherwise, do not use a hyphen, even if the following word starts with ‘r’.

inter-group, international, interrelate

intra-

Use a hyphen if following word starts with ‘a’.

intra-abdominal, intra-acinar

meta-

Use a hyphen if following word starts with a vowel.

meta-analysis, metastasis

micro-

Either joined to the word it modifies or uses a hyphen (it does not stand alone)

microbiology, microcirculation, microfilaria,
micro-organism (UK spelling), microorganism (US spelling)

mid- Use a hyphen for all words that have 'mid-' as a prefix, except for common words that are never hyphenated (e.g. midnight).

mid-urethral, mid-term, mid-treatment

midnight, midwife

mini-

Either joined to the word it modifies or uses a hyphen (it does not stand alone)

minitracheostomy, mini-mental state examination

multi-

Either joined to the word it modifies or uses a hyphen (it does not stand alone)

multicentre, multi-agency

non-

Hyphenate if ‘non’ qualifies more than one word.
 

Use of hyphen is optional if 'non' qualifies only one word.

Do not use a hyphen with Latin phrases.

Note: Latin phrases should be avoided where possible.

non-insulin dependent, non-profit making

non-smoker, nonviolent

materia non medica, non sequitur

post-

Either joined to the word it modifies or uses a hyphen if the following word starts with 't' (it does not stand alone)

postgraduate, postorbital, postoperative, post-treatment

pre-

A hyphen is normally used when the following word starts with ‘e’ or ‘i'.


 

Established combinations are generally one word (except when the word begins with an ‘e’ or an 'i').
 

In other combinations, the hyphen is not necessary but is freely used if the compound is one made for the occasion (might be better to rephrase), or if any peculiarity in its form might prevent its elements from being instantly recognized.

pre-eclampsia, pre-embryo, pre-exist, pre-exposure, pre-install, pre-industrial

prearranged, prenatal, preoccupy, preschool, pre-empt

pre-medication, pre-tax, pre-war

re-

Use a hyphen if the following word starts with ‘e’.
 

 

Rephrase when there would be confusion with another word.

re-edit, re-educate, re-establish, re-enter, re-enlist

re-cover (cover again) and recover (get better)

self-

All compound words with ‘self’ as a prefix should be hyphenated.

self-limited
self-confidence

semi-

Use a hyphen if the following word starts with ‘i’.

semi-independent, semicolon

sub-

Use a hyphen if the following word starts with ‘b’.

sub-basal, sub-breed (note: sub-Saharan is one exception)

un-

Words starting with ‘un-‘ are generally one word.
 

Rephrase or use a hyphen when there would be confusion with another word.

unnoticeable, unopened, unpaid, unpick

unionized (with a union) and un-ionized (without ions)

Section info
Contact
Elizabeth Royle (eroyle@cochrane.org)
Describe change
Advice on hyphenation of 'co' changed: hyphens can now be used when the word following starts with a vowel. Well established words such as 'coincidence' should not be hyphenated.
Advice on hyphenation of 'mid' added: hyphens should be used for all words that have 'mid-' as a prefix, except for common words that are never hyphenated (e.g. midnight)
Change date
19 September 2019