Prefixes are letters which we add to the beginning of a word to make a new word with a different meaning. Prefixes can, for example, create a new word opposite in meaning to the word the prefix is attached to. They can also make a word negative or express relations of time, place or manner. Here are some examples:
type of meaning
place (outside of/beyond)
manner (too much)
I’m sorry I was unable to attend the meeting.
Non-payment of fees could result in a student being asked to leave the course.
Has anyone ever really met an extraterrestrial being? (meaning a being from another planet)
The meat was overcooked and quite tasteless.
The most common prefixes
anti-government, anti-racist, anti-war
reverse or change
de-classify, decontaminate, demotivate
reverse or remove
disagree, displeasure, disqualify
reduce or lower
il-, im-, in-, ir-
illegal, impossible, insecure, irregular
very big, important
megabyte, mega-deal, megaton
midday, midnight, mid-October
misaligned, mislead, misspelt
overcook, overcharge, overrate
outdo, out-perform, outrun
in favour of
reconsider, redo, rewrite
at a distance
remove, reverse, not
undo, unpack, unhappy
less than, beneath
make or move higher
Writing prefixes: hyphens (super-hero or supermodel)
There are no absolute rules for when to use a hyphen or when to write a prefixed word as one whole word (see the examples in the table). A good learner’s dictionary will tell you how to write a prefixed word.