A prefix is a letter or a group of letters placed at the beginning of words to create a derivative (a similar word with a different meaning).

Adding the prefix in- to the word visible changes the meaning of the word.
Below is a list of prefixes used to create words that mean the opposite of their root form.
Prefixes |
Root words |
In context |
dys- |
function |
Carmen didn’t grow up in a dysfunctional family. |
a- |
moral |
Her parents are not amoral people. |
ab- |
norm |
But Carmen always felt somewhat abnormal. |
de- |
active |
She once deactivated* all her social media and cellphone. |
dis- |
appear |
She disappeared* from the internet for a while. |
im- |
possible |
Reaching out to her became impossible. |
in- |
visible |
But she preferred feeling invisible. |
non- |
stop |
Her sister tried calling nonstop. |
mal- |
function |
She even believed Carmen’s cellphone was malfunctioning*. |
anti- |
social |
Because it wasn’t like Carmen to be antisocial. |
mis- |
handle |
Carmen mishandled* the situation. Her entire family was worried. |
ir- |
responsible |
Acting the way she did was irresponsible. |
un- |
conditional |
But that’s only because they love her unconditionally*. |
*Suffixes were added at the end of some of the words to fit the context.
Here are examples of prefixes to add to root words to indicate their size or quantity.
Prefixes |
Meaning |
Root words |
In context |
micro- |
miniature |
biology |
Carmen studied microbiology for a year. |
macro- |
large |
biology |
She also studied macrobiology for a while. |
mega- |
large |
hit |
Carmen’s sister's first song was a megahit. |
giga- |
quantity |
byte |
Carmen’s new computer has a storage of 128 gigabytes. |
mini- |
miniature |
bus |
She owns a minibus. |
Add the following numerical prefixes to describe units of measurement.
Prefixes |
Meaning |
Example |
milli- |
.001m |
millimetre |
centi- |
.01m |
centimetre |
deci- |
1dB |
decibel |
kilo- |
1000m |
kilometre |
uni- |
1 |
unicycle |
mono- |
1 |
monotone |
bi- |
2 |
bicycle |
tri- |
3 |
tricycle |
semi- |
.5 |
semiannual |
multi- |
many |
multimillionaire |
poly- |
many |
polyglot |
Prefixes |
Meaning |
Root words |
In context |
pre- |
before |
view |
Carmen watched the preview of the movie before going to the movie theatre. |
post- |
after |
graduate |
After college, she didn’t pursue a postgraduate degree. |
fore- |
before |
cast |
Carmen checks the weather forecast every day. |
mid- |
middle |
night |
She usually goes to bed around midnight. |
Prefixes |
Meaning |
Root words |
In context |
exo- |
external |
skeleton |
In college, Carmen worked on an exoskeleton prototype. |
endo- |
internal |
scope |
Next week, Carmen has an endoscopy*. |
inter- |
between/among |
nation |
Her sister is an international* pop star. |
intra- |
within |
mural |
In college, Carmen participated in a lot of intramural activities. |
peri- |
around |
meter |
When her goats ran away, the police searched Carmen’s home perimeter. |
circum- |
around |
vent |
When Carmen arrived on site, the policemen were circumventing* them. |
sub- |
below |
marine |
Carmen once traveled in a submarine. |
trans- |
across |
Atlantic |
Next, she wants to go on a transatlantic cruise. |
in- |
inside |
door |
Carmen does not like to be indoors. |
out- |
outside |
door |
She much prefers being outdoors. |
*A suffix was added at the end of a word to fit the context.
Add the following prefixes to root words to increase their strength.
Prefixes |
Meaning |
Root words |
In context |
under- |
insufficiency |
estimate |
People often underestimate the joy animals can bring them. |
over- |
extremely |
joy |
She is overjoyed* when one of her goats falls asleep in her arms. |
hyper- |
extremely |
active |
Carmen was diagnosed with hyperactivity*. |
out- |
more |
go |
She is very outgoing*. |
super- |
extremely |
star |
Her sister is the superstar of the family. |
extra- |
extremely |
ordinary |
She believes she is living an extraordinary life. |
*A suffix was added at the end of a word to fit the context.

Adding the prefix co- to the noun pilot indicates that there is a second pilot on the minibus.

Adding the prefix co- to the verb operate indicates that Carmen and her sister worked together to accomplish a task.
Prefixes |
Root words |
Reflexive pronouns |
my |
self |
myself |
them |
selves |
themselves |
Prefixes |
Root words |
In context |
pro- |
active |
Carmen is a proactive person. |
em- |
bitter |
She doesn’t let situations or people embitter her. |
per- |
mission |
When Carmen was younger, she used to ask permission for everything. |
homo- |
phone |
She would also confuse the homophones “two” and “too.” |
hetero- |
gene |
Carmen likes travelling with heterogeneous groups. |
auto- |
mobile |
She sold her automobile five years ago. |
re- |
turn |
Her sister should return from touring in a couple of weeks. |
ex- |
tend |
But her manager apparently wants to extend it for another six months. |