Prefixes are affixes that go in front of root words to create new meanings. Prefixes can include a point in time or space (as in outside, prehistoric), the opposite (undo, inept), the number (trifocal, bifocal, unicycle), and many other things. Unlike suffixes, prefixes do not change the part of speech or the spelling of the word.
Below are some common prefixes and their meanings.
Prefix: Meaning: Examples:
anti- opposite. antithesis, antifreeze
bi- two. bifocal, biped
post- after. postmodern, postwar
pre- before. prepay
re- again. remake, review
sub- below. submarine, sub-zero
super- above, over superlative, superscript
tri- three triathlon, trident
ultra- beyond. ultralight, ultraviolet
un- reverse undo, unkept
uni- one uniform, unicycle