A prefix is a letter or a group of letters fixed prior to the word. Pre-fix itself is a prefix.
Prefix Meaning Examples
a-, an- without, lack-of, not amoral,anonymous
anti- against, opposing antivirus
ante- before anteroom
auto- self autobiography
circum- around circumnavigation
co-/com-/con- with, together coexist, commiserate, contact
contra- against, opposing contradict
de- reverse deactivate
em-, en- cause to, put into embrace, envelope
epi- upon, close to, after epicenter, episcopate, epidermis
ex-/exo- out exhale, exoskeleton
extra- beyond extracurricular
dis- removal disconnect
fore- before forecast, forehead
hetero- different heterogeneous
homo- same homophone
hyper- extreme hyperactive
infra- beneath, below infrastructure, infrared
inter- between interactive
il-/im-/in-/ir- not, without illegal, immature, injustice, irrelevant
mega- large megastar
micro- small microscope
mid- middle midnight
mis- incorrect misuse
mono- one monotone
non- not, without nonfiction
omni- all, every omniscient, omnipresent
over- too much overactive
para- beside parachute
post- after postscript
pre- before prefix, predict
pro- forward project, prologue
re- again re-consider
semi- half, partial semiconductor, semester
sub- below submarine
therm- heat thermometer
trans- across, change transport, transgender
tri- three triangle, tripod
un- not, opposite unkind, unresponsive
uni- one, single unicorn, unicellular