A little guide to English prefixes

English prefix 'semi-'

This tree is almost semicircular. In the word ‘semicircle’ the prefix ‘semi-‘ means ‘half’ – half a circle.


A prefix is an affix – a group of letters – added to the beginning of a word, or before a word root, to make another word

In the word ‘unhappy’, ‘un-‘ is a prefix.

In the word ‘rewrite’, ‘re-‘ is a prefix.

If you understand the meanings of English prefixes this can help you work out the meanings of new vocabulary.

For example:

‘un-‘ means ‘not’

‘un-‘ + ‘happy’ = ‘unhappy’ or ‘not happy’


Common English prefixes and their meanings


Prefix Meaning Examples
a- on, in, at, to, in the specified state or manner ajar, abed, ablaze, aloud
 a-  an-  (having) no, not, without  amoral, asexual, anaesthetic
 ante-  before  antecedent, anteroom
 anti-  against  antifreeze, antibiotic
 auto-  self  autocorrect, automatic
 bi-  two  bifocal, bicycle
 co-  together, with
 cooperate, co-pilot, coordinate
 com-  together, with  combination, community, companion, complement
 contra-  against, contrasting
 contraception, contradiction
 dis-  not (opposite of)
 disbelief, discomfort, disappear, disagree
 ec- and  ex-
 out of/former
 ectopic, extract, exodus, ex-president
homo-  same  homonym, homophone
hyper-  excessive, over, more  hyperactive, hyperthermia, hyperbole, hypercritical
hypo-  under, beneath, less than normal  hypodermic, hypotension, hypoallergenic
il- im- in- ir-  not,without  illegal, illusion, impossible, immoral, injustice, irrigate,     irresponsible
 inter-  between  interact, interplay, intersection, interlock
met- or meta-  behind or beyond, changed/transformed
 metaphor, metamorphosis
mis- wrongly, not, wrong, bad, lack of misjudge, misfire, misunderstand, misdeed, misgiving
non- not, without non-existent, non-alcoholic, non-fiction, nonconformity, non-stick, nonsense
pre- earlier than, before, in front of prehistoric, prefabricate, prefix, precede
post- after, subsequent, later postdate, postmortem, posthumous, postgraduate
re- again, back, away or down return, reprint, rewrite, recall, recede
semi- half, partly semicircle, semiconscious, semidarkness
sub- under, beneath, below, incomplete or inferior submarine, subsoil, subhuman, subculture
trans- across, through, change transatlantic, transform
un- not, opposite of unwashed, unloved, unfriendly, unbiased, uncool


The origins of prefixes

Prefixes have interesting origins, showing some of the many influences on English.

For example:



‘mis-‘ as in misgovern



‘in-‘ as in inactive

‘post-‘ as in postnatal, postmortem, postwar

‘pre-‘ as in preconceive



‘a-‘ as in amoral  

‘anti-‘ as in anti-war

‘bio-‘ as in biology, biopsy

‘geo-‘ as in geography 

‘meta-‘ as in metaphysical


Language is constantly changing and adapting and you’re probably familiar with one fairly new prefix that’s used for all sorts of things today, the prefix e- (electronic) as in:







and e-petition


In tomorrow’s post we’ll look at the guidelines for hyphenating prefixes 🙂




  1. I love looking at the origins of words, and you make this really interesting Angela.
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  2. Very interesting Angela, Thank you 🙂
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  3. I didn’t know that ‘a’, ‘mis’ and ‘un’ before words were prefixes.

    Interesting post, thank you.
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  4. I like words with prefixes where the prefix has become so ‘affixed’ that I don’t think of the prefix as a prefix at all – like in the word misbegotten.

    Do we use the un-affixed word? It seems archaic. Do we say ‘He was begotten of the king and queen of Persia.’ ?
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    • Me too, David. When I was writing this post and thinking about prefixes I really noticed how many prefixes there are that, as you say, we just don’t even think of them as prefixes anymore.

      I think it would be ‘He was beget…'(?) It’s definitely a word we don’t hear much – except perhaps in the Bible?

      It’s a good word though 🙂

  5. It’s so interesting to ‘observe’ our language from the perspective of someone who is not a native English speaker. I had the fortune to take Latin at school, which teaches you a great deal about English (and other) languages. I value this more an more as I get older.
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  6. Hi Angela, very interesting to see how the prefix e is evolving 🙂
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