Prefix – is a letter or a group of letters added to the beginning or the stem of the word. For example, the word “unsure” has a prefix “un” which means “not” with a root word “sure.” Hence, the word “unsure” means “not sure.”

Read this important table which contains information and examples about prefixes.


Prefix Meaning Example Meaning of the word
anti- against antibacterial Intended to kill or reduce the harmful effects of bacteria.
auto- self autobiography An account of a person’s life written by that person.
bi- two bicycle A vehicle with two wheels.
dis- not disagree to have a different opinion or be unable to agree.
ex- out, former exhale to breathe out air.
il- not illegal against the law.
im- not improper being against a law or a rule; dishonest or illegal.
in- not invisible impossible to see.
inter- between interchangeable able to be exchanged with each other.
ir- not irrelevance the fact that something is not related to what is being discussed or considered.
micro- small microcomputer a small computer containing a microprocessor.
mis- wrong misdirect to send something to the wrong place or aim something in the wrong direction.
mono- one monogamy marriage with one person.
non- not nonpoisonous not having the properties or effects of poison.
poly- many polytheist one who believes in a plurality of gods.
post- later, behind postgraduate a student who has already received one degree and is studying at a university for a more advanced degree.
pre- before prehistory History of humankind in the period before recorded history.
pro- for, forward, before proactive Acting in advance to deal with an expected difficulty; anticipatory.
re- again reconstruct to construct again; rebuild.
semi- half semiconscious Partially conscious; not completely aware of sensations.
sub- under subcontractor someone who enters into a subcontract with the primary contractor.
tri- three triathlon an athletic contest in which each athlete competes in three different events: swimming, cycling, and running.
un- not unbelievable not to be believed; incredible.
uni- one unisize in one size only, to fit most people of relatively average build.


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