Word Roots, Prefixes, and Suffixes

One of the most powerful vocabulary skills you can develop for the SET is the ability to break words apart. If you understand roots, prefixes, and suffixes, you can work out the meaning of unfamiliar words — even ones you have never seen before. This is especially valuable in the SET Stage 1 comprehension, where questions may ask you to explain what a word means in context.

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What Is a Word Root?

A root (or root word) is the core part of a word that carries its main meaning. Many English roots come from Latin and Greek.

Common Latin Roots

Root	Meaning	Example Words
aud	hear	audience, audible, auditorium
dict	say, speak	dictionary, predict, contradict
duc/duct	lead	conduct, educate, introduce
port	carry	transport, portable, export
scrib/script	write	describe, manuscript, inscription
vis/vid	see	visible, video, evidence
rupt	break	disrupt, interrupt, erupt
struct	build	construct, instruct, structure
spec/spect	look	spectacle, inspect, specimen
tract	pull, drag	attract, extract, tractor

Common Greek Roots

Root	Meaning	Example Words
auto	self	autobiography, automatic, autonomy
bio	life	biology, biography, biodegradable
chron	time	chronological, chronicle, synchronise
graph/gram	write, draw	photograph, diagram, telegram
phon	sound	telephone, microphone, symphony
tele	far, distant	television, telescope, telecommunication
micro	small	microscope, microbe, microchip
poly	many	polygon, polyglot, polytechnic
mono	one, single	monologue, monotone, monarch
therm	heat	thermometer, thermal, thermostat

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Prefixes

A prefix is a group of letters added to the beginning of a root word to change its meaning. The spelling of the root word does not change when you add a prefix.

Negative Prefixes (Making a Word Mean the Opposite)

Prefix	Meaning	Examples
un-	not, opposite	unhappy, unable, uncertain
in-	not	incomplete, incorrect, invisible
im-	not (before b, m, p)	impossible, immature, impatient
il-	not (before l)	illegal, illogical, illiterate
ir-	not (before r)	irregular, irresponsible, irrelevant
dis-	not, opposite, remove	disagree, disappear, disconnect
mis-	wrong, badly	misunderstand, misplace, misbehave
non-	not	nonsense, non-fiction, non-stop

Tip: Notice how "in-" changes to "im-", "il-", or "ir-" depending on the first letter of the root word. This is called assimilation — the prefix adjusts to make the word easier to say.

Other Important Prefixes