WKWord Knowledge

Prefixes & Suffixes

Knowing 20 common prefixes and suffixes gives you a working guess on hundreds of unfamiliar ASVAB words.

Formula Reference

  • Prefix = word beginning that modifies core meaning (mis- = wrong, pre- = before, un- = not)
  • Suffix = word ending that signals part of speech or meaning (-tion = noun/act, -ous = adjective/full of, -fy = verb/to make)
  • High-value negative prefixes: un-, dis-, in-/im-, non-, anti-, mal-
  • High-value number prefixes: uni- (1), bi- (2), tri- (3), quad- (4), multi- (many)
  • Common suffix signals: -ible/-able = capable of, -ful = full of, -less = without, -ist = one who

Why this matters more than flashcards

Flashcards work when you've seen the word before. Prefixes and suffixes work on words you've never seen. The ASVAB will throw unfamiliar words at you — this is the tool that keeps you from guessing blind.

English borrows heavily from Latin and Greek. The same building blocks show up in thousands of words across science, law, military terminology, and everyday speech. Learn the blocks, decode the words.

The prefixes worth memorizing first

Negative/reversal:

  • un- — unable, unfit, unkempt
  • dis- — displace, disloyal, disrupt
  • mis- — misjudge, misconduct, mislead
  • mal- — malfunction, malicious, malnourished
  • non- — noncombatant, nonessential, nonfatal
  • anti- — antidote, antiaircraft, antisocial

Time and position:

  • pre- — predict, precaution, premature
  • post- — postwar, postpone, posterior
  • sub- — submarine, subordinate, substandard
  • inter- — intercept, intervene, international
  • trans- — transport, transfer, transcend

Degree and size:

  • over- — overestimate, overpowered
  • hyper- — hyperactive, hypersensitive
  • micro- — microscopic, microcosm

Suffixes that signal meaning

-ous (full of): hazardous, conspicuous, strenuous -ful (having): resourceful, forceful, dreadful -less (without): reckless, careless, relentless -able / -ible (capable of): capable, flexible, compatible -tion / -sion (act or state): mission, operation, condition -ist (one who): strategist, specialist, antagonist -ify / -fy (to make): fortify, clarify, magnify

Worked breakdown: dissect before you guess

Take noncombatant: non- (not) + combat + -ant (one who does). A noncombatant = one who does not combat — a civilian or medical personnel in a military context.

Take subversive: sub- (under/against) + vers (to turn) + -ive (tending to). Subversive = tending to undermine or turn against authority.

Two or three parts, decoded separately, give you the full meaning.

Study priority

Focus on the 30 most common Latin and Greek prefixes first. They cover the majority of hard ASVAB words. Add suffixes second — they're easier because they mostly signal part of speech, not meaning. Roots come third (see the Root Words guide).

Common Pitfalls

  • Assuming a prefix is always negative — 'in-' can mean 'not' (inactive) or 'into' (insert)
  • Stripping the prefix and not recognizing the root — break 'mal-odor-ous' into all three parts
  • Confusing -ible and -able — both mean 'capable of' and the distinction is spelling, not meaning
  • Stopping after identifying the prefix without checking whether the answer actually fits the sentence

Worked Examples

Q1: MALEVOLENT most nearly means: (A) powerful (B) wishing harm (C) easily fooled (D) widely known

Answer: Mal- = bad/evil. Volent comes from Latin 'velle' (to wish). Malevolent = wishing evil toward others. Answer: B

Q2: PRECLUDE most nearly means: (A) introduce (B) follow up (C) prevent beforehand (D) repeat

Answer: Pre- = before. Clude comes from Latin 'claudere' (to close). To preclude = to close off before it happens, i.e., prevent. Answer: C

Q3: INDEFATIGABLE most nearly means: (A) lazy (B) tireless (C) forgetful (D) unreliable

Answer: In- = not. De-fatigable = capable of being fatigued. Indefatigable = not capable of being fatigued — tireless. Answer: B

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