Word roots, prefixes and suffixes for ASVAB Word Knowledge
Many test-level English words are built from Latin and Greek parts, so knowing the 80 or so common prefixes, roots and suffixes lets you estimate the meaning of words you have never studied. Break the word into parts, give each part its meaning, then check your estimate against the sentence and the choices.
How do word parts help on ASVAB Word Knowledge?
Word parts let you turn an unknown word into a rough meaning, which is often enough to choose between four answers. Take "retrospect." You may never have studied it, but retro- is Latin for backward and spect comes from the Latin verb for look, so the word means looking back. In "In retrospect, we should have left earlier," that reading fits perfectly.
A word usually has up to three kinds of parts:
- Prefix: attached to the front. It often changes direction, number or sense: un-, re-, pre-, sub-.
- Root: the core that carries the main meaning: port (carry), dict (say), vis (see).
- Suffix: attached to the end. It often tells you the part of speech: -ous makes an adjective, -tion makes a noun, -ize makes a verb.
The tables below list the parts that show up most in test-level vocabulary. Each origin is given as Latin, Greek or Old English, with the source word where it helps you remember.
Which prefixes are most useful to know?
These prefixes appear in hundreds of common words. Learn the meaning and one example word for each.
| Prefix | Origin | Meaning | Example words |
|---|---|---|---|
| a-, an- | Greek | without, not | atypical, anonymous |
| ante- | Latin | before | antecedent, anteroom |
| anti- | Greek | against, opposite | antidote, antisocial |
| auto- | Greek | self | automatic, autonomy |
| bene- | Latin | well, good | benefit, benevolent |
| bi- | Latin | two | bilingual, bicycle |
| circum- | Latin | around | circumference, circumvent |
| contra-, counter- | Latin | against | contradict, counteract |
| de- | Latin | down, away, reverse | descend, deflate |
| dis- | Latin | apart, not | dismiss, dishonest |
| ex-, e- | Latin | out, out of | exit, expel, emit |
| hyper- | Greek | over, beyond | hyperactive, hypercritical |
| hypo- | Greek | under, below | hypothermia, hypodermic |
| in-, im-, il-, ir- | Latin | not (also: in, into) | inactive, impossible, illegal, irregular |
| inter- | Latin | between, among | interstate, intervene |
| intra- | Latin | within | intramural, intravenous |
| mal- | Latin | bad, badly | malfunction, malnourished |
| mis- | Old English | wrongly | misread, mislead |
| mono- | Greek | one, single | monotone, monopoly |
| multi- | Latin | many | multiply, multicolored |
| omni- | Latin | all | omnivore, omnipresent |
| poly- | Greek | many | polygon, polysyllabic |
| post- | Latin | after | postpone, postwar |
| pre- | Latin | before | preview, precaution |
| re- | Latin | again, back | rebuild, retract |
| sub- | Latin | under, below | submarine, subordinate |
| super- | Latin | above, beyond | supervise, superfluous |
| syn-, sym- | Greek | together, with | synchronize, sympathy |
| trans- | Latin | across | transport, transfer |
| un- | Old English | not, reverse of | unclear, undo |
The prefix in- has two different meanings. In "inactive" it means not; in "inhale" and "inflammable" it means in or into. Inflammable means able to catch fire, the same as flammable.
Which word roots should you learn for the ASVAB?
Roots carry the core meaning, so they give the biggest return for your study time. These come from Latin and Greek verbs and nouns; the source word is in parentheses.
| Root | Origin | Meaning | Example words |
|---|---|---|---|
| aud | Latin (audire) | hear | audible, audience |
| bio | Greek (bios) | life | biology, biography |
| cap, capt, cept | Latin (capere) | take, seize | capture, intercept |
| ced, cede, ceed, cess | Latin (cedere) | go, yield | proceed, recede, concession |
| chron | Greek (chronos) | time | chronic, chronological |
| cred | Latin (credere) | believe | credible, incredulous |
| dic, dict | Latin (dicere) | say, speak | predict, contradict |
| duc, duct | Latin (ducere) | lead | conduct, deduce |
| fid | Latin (fides) | faith, trust | confide, fidelity |
| frag, fract | Latin (frangere) | break | fragile, fracture |
| geo | Greek (ge) | earth | geography, geology |
| graph | Greek (graphein) | write, draw | autograph, graphic |
| ject | Latin (iacere) | throw | eject, reject, project |
| log, logy | Greek (logos) | word, reason, study of | dialogue, geology |
| loqu, locut | Latin (loqui) | speak | eloquent, loquacious |
| man, manu | Latin (manus) | hand | manual, manuscript |
| mit, miss | Latin (mittere) | send | transmit, dismiss |
| mort | Latin (mors, mortis) | death | mortal, mortuary |
| path | Greek (pathos) | feeling, suffering | sympathy, apathy |
| pend | Latin (pendere) | hang | pendant, suspend |
| phon | Greek (phone) | sound, voice | telephone, phonics |
| port | Latin (portare) | carry | portable, transport |
| rupt | Latin (rumpere) | break | erupt, interrupt |
| scrib, script | Latin (scribere) | write | describe, transcript |
| sens, sent | Latin (sentire) | feel, perceive | sensory, consent |
| sequ, secut | Latin (sequi) | follow | sequence, consecutive |
| spec, spect | Latin (specere) | look | inspect, spectator |
| struct | Latin (struere) | build | construct, obstruct |
| tract | Latin (trahere) | pull, draw | tractor, retract |
| ven, vent | Latin (venire) | come | intervene, convention |
| vers, vert | Latin (vertere) | turn | reverse, divert |
| vid, vis | Latin (videre) | see | evident, visible |
| viv, vit | Latin (vivere, vita) | live, life | revive, vital |
| voc, vok | Latin (vocare) | call | vocal, revoke |
What do common suffixes tell you about a word?
A suffix usually tells you the part of speech, which is a fast way to remove choices. If the test word ends in -ous, the answer is almost always an adjective too.
| Suffix | Usually makes | Meaning | Example words |
|---|---|---|---|
| -able, -ible | adjective | can be, able to be | readable, visible |
| -ous, -ious | adjective | full of, having | dangerous, cautious |
| -ful | adjective | full of | fearful, skillful |
| -less | adjective | without | careless, fearless |
| -ive | adjective | tending to | active, defensive |
| -ic, -ical | adjective | relating to | heroic, historical |
| -tion, -sion | noun | act or state of | action, tension |
| -ment | noun | act, result or means of | agreement, equipment |
| -ity, -ty | noun | state or quality of | clarity, loyalty |
| -ness | noun | state or quality of | kindness, readiness |
| -ist, -er, -or | noun | person who | chemist, driver, inspector |
| -ology | noun | study of | biology, psychology |
| -cide | noun | killing, killer (Latin caedere, to kill) | pesticide, homicide |
| -phobia | noun | fear of (Greek phobos) | claustrophobia, arachnophobia |
| -ize, -ise | verb | to make or become | modernize, finalize |
| -fy, -ify | verb | to make (Latin facere) | simplify, clarify |
| -ate | verb (often) | to act on, to cause | activate, separate |
| -ly | adverb | in a certain way | quickly, carefully |
Example: Which choice is the best synonym for audible? (A) loud (B) able to be heard (C) musical (D) spoken clearly
- Split the word: aud + ible.
- The root aud comes from Latin audire, to hear. The suffix -ible means able to be.
- Combine: able to be heard.
- Check the traps. (A) loud is too strong: a whisper can still be audible. (D) spoken clearly adds speech, but audible applies to any sound.
Answer: (B) able to be heard.
How do you break down an unfamiliar word step by step?
Find the prefix, find the suffix, look at what is left in the middle, then put the meanings together and test the result in the sentence. Here are three worked examples.
Example: The guide chose a route that would circumvent the flooded valley. Circumvent most nearly means: (A) cross (B) go around (C) measure (D) drain
- Prefix: circum-, Latin for around (as in circumference).
- Root: vent, from Latin venire, to come.
- Combine: to come around, that is, to go around something.
- Test in the sentence: a route that would go around the flooded valley. That makes sense; nobody wants to cross a flood.
- Remove the rest: (A) cross is the opposite idea, and (C) and (D) have no link to the parts.
Answer: (B) go around.
Example: His incredulous look showed what he thought of the excuse. Incredulous most nearly means: (A) amazed (B) unwilling to believe (C) angry (D) amused
- Prefix: in-, here meaning not.
- Root: cred, from Latin credere, to believe.
- Suffix: -ous, an adjective ending meaning full of or having.
- Combine: not believing. The sentence is about his reaction to an excuse, which fits doubt.
- Watch the near miss. "Incredible" means hard to believe and describes the thing. "Incredulous" describes the person who does not believe it.
Answer: (B) unwilling to believe.
Example: The manager had to retract the statement after the error was found. Retract most nearly means: (A) take back (B) repeat (C) explain (D) publish
- Prefix: re-, Latin for back or again.
- Root: tract, from Latin trahere, to pull or draw.
- Combine: to pull back. For a statement, that means to take it back or withdraw it.
- Test: "had to take back the statement after the error was found." The sentence holds. (B) repeat uses the "again" sense of re-, which does not fit an error.
Answer: (A) take back.
When a prefix has two meanings, like re- (again or back), test both in the sentence. The sentence decides which one the writer meant.
When do word roots mislead you?
Roots point to a likely meaning, but English has borrowed and changed words for centuries, so some words drift away from their parts. Watch for these cases.
- Two roots that look alike. "Pedestrian" comes from Latin pes, pedis (foot). "Pediatric" comes from Greek pais, paidos (child). Same letters, different origins.
- Prefixes with two meanings. "Invaluable" means extremely valuable, so valuable that no price can be put on it. It does not mean worthless. "Inflammable" means flammable.
- Meanings that shifted. "Nice" once meant foolish. "Decimate" originally referred to killing one in ten (Latin decem, ten) but today usually means to destroy a large part of something.
- Look-alike words with no shared root. "Adverse" (harmful) and "averse" (unwilling) look close, and both come from Latin vertere (turn) with different prefixes, so the parts alone will not separate them. Learn pairs like this as pairs.
That is why the method always ends with the sentence. Use the parts to form a guess, then let the context confirm it. The context clues guide covers how to read the sentence for help.
How should you study roots without wasting time?
Learn one root at a time with three or four words that share it, and review the families on a schedule. Memorizing a long table in one sitting does not stick.
- Pick five roots a day from the tables above.
- For each root, write three words you already know that contain it. For spect: inspect, spectator, perspective.
- Add one new word from the vocabulary list that uses the root, such as circumspect (looking around, so careful) or retrospect.
- Quiz yourself the next day by covering the meaning column.
- Practice on real items. Use the Word Knowledge practice and, for every word you miss, check whether a root would have helped.
For a wider plan that covers both verbal subtests, see the Word Knowledge strategies page and the study plan by subtest.
Practice questions
Work each one on paper first, then open the explanation. These are original AptiStep items, not real ASVAB questions.
Using word parts, which is the best meaning of "transmit"?
- to send across
- to break apart
- to look back
- to carry inside
Show answer and explanation
Answer: A. to send across
Split the word: trans- means across (Latin), and mit comes from Latin mittere, to send. Together they give to send across, as when a radio transmits a signal. Break apart would need rupt or fract, and look back would need retro and spect.
The prefix in "malnourished" tells you the person is:
- well fed
- badly fed
- fed too often
- never fed
Show answer and explanation
Answer: B. badly fed
The prefix mal- comes from Latin and means bad or badly, as in malfunction. Malnourished therefore means badly or poorly fed. Bene- would mean well, hyper- would suggest too much, and a- or un- would be needed for never.
Which word contains a root meaning "turn"?
- predict
- portable
- divert
- construct
Show answer and explanation
Answer: C. divert
Divert contains vert, from Latin vertere, to turn; to divert traffic is to turn it aside. Predict contains dict (say), portable contains port (carry), and construct contains struct (build), so only divert has the turn root.
Apathy most nearly means:
- anger
- deep sadness
- strong interest
- lack of feeling or interest
Show answer and explanation
Answer: D. lack of feeling or interest
Break it down: a- is a Greek prefix meaning without, and path comes from Greek pathos, feeling. Without feeling gives lack of interest or concern. Strong interest is the opposite, and anger and sadness are strong feelings, not the absence of feeling.
A "loquacious" passenger is most likely:
- very talkative
- very quiet
- easily confused
- often late
Show answer and explanation
Answer: A. very talkative
The root loqu comes from Latin loqui, to speak, as in eloquent. The suffix -ous means full of, so loquacious means full of talk, or very talkative. Very quiet is the opposite, and the other two choices have no link to the word parts.
Which pair of words shares a root meaning "believe"?
- credit and incredulous
- chronic and chronicle
- fragile and fracture
- vocal and revoke
Show answer and explanation
Answer: A. credit and incredulous
Credit and incredulous both contain cred, from Latin credere, to believe. The other pairs also share roots, but different ones: chron means time, frag and fract mean break, and voc and vok mean call. Only the first pair matches the meaning believe.
An "invaluable" tool is one that is:
- worthless
- cheap to replace
- extremely useful
- not yet priced
Show answer and explanation
Answer: C. extremely useful
This is a classic trap. Although in- often means not, invaluable means so valuable that no price can be put on it, so extremely useful is right. Worthless is the opposite. The word parts alone would mislead you here, which is why you always check the sense.
The suffix in "simplify" tells you the word is most likely a:
- noun naming a person
- verb meaning to make
- adjective meaning full of
- adverb describing how
Show answer and explanation
Answer: B. verb meaning to make
The suffix -fy (or -ify) comes from Latin facere, to make, and forms verbs: simplify means to make simple, clarify means to make clear. A person noun would end in -er, -or or -ist, an adjective in -ous, and an adverb in -ly.
Frequently asked questions
How many roots do I need to know for the ASVAB?
There is no official number. The roughly 80 parts on this page cover many of the Latin and Greek words you will meet in general test vocabulary, and learning five a day takes a little over two weeks.
Are roots enough to pass Word Knowledge?
No single method is enough. Roots help with unfamiliar words, but you still need a working vocabulary and the habit of checking meaning in the sentence. See the Word Knowledge strategies.
Why do some prefixes have two meanings?
English took the same-looking prefix from different sources or uses. Latin in- meant both not and into, so inactive and inhale use different senses. The sentence tells you which applies.
Where can I practice with real-format questions?
The official site has a sample questions page, and AptiStep has free original Word Knowledge practice.
Sources
Checked November 14, 2026. AptiStep is an independent study site; confirm anything that affects your enlistment with a recruiter.
- Official ASVAB: What to Expect
- Official ASVAB: Understanding ASVAB Scores
- Official ASVAB: Sample Questions