Words you have never seen before will always appear in vocabulary questions and reading passages at highly selective universities. Since it is impossible to memorize everything, you need the skill of building meaning from prefixes, suffixes, and roots. This is a practical skill for “breaking down an unfamiliar word on the spot.”
Basic Rules
Prefixes meaning negation or opposition: un- / in- (im-, il-, ir-) / dis- / non- / mis- (wrong) / anti- (against)
Prefixes meaning degree or direction: over- (excess) / under- (insufficiency) / out- (exceed) / sub- (lower) / super- (exceed) / trans- (across) / inter- (between) / re- (again) / pre- (before) / post- (after)
Meanings of roots: -spect (see: respect, inspect, prospect) / -duce/duct (lead: introduce, conduct, reduce) / -mit/mis (send: transmit, permit, dismiss) / -tain (keep: maintain, sustain, obtain) / -vert (turn: convert, revert, divert) / -cred (believe: credible, incredible) / -sist (stand: consist, resist, insist)
Noun-forming suffixes: -tion/-sion (action or state) / -ness (state) / -ity (quality) / -ment (action or result)
Adjective-forming suffixes: -able/-ible (possible) / -ous/-ive (having a quality) / -al (related to)
For an unfamiliar word, breaking it down into “prefix + root + suffix” and guessing its general meaning and part of speech is a practical test-taking skill.
The company's overreliance on a single supplier proved to be a critical weakness. (The company's excessive dependence on a single supplier proved to be a serious weakness.) ← over- (excess) + reliance
The theory was later disproved by new experimental evidence. (The theory was later shown to be false by new experimental evidence.) ← dis- (negation) + proved
Scientists are still trying to determine the precise mechanism that underlies the disease. (Scientists are still trying to clarify the mechanism underlying the disease.) ← under- (below) + lies
The report was widely regarded as an oversimplification of a complex issue. (The report was widely regarded as an excessive simplification of a complex issue.) ← over- + simplification
※ Even for an unfamiliar word, you can grasp its “degree” and “direction” from the prefix
Points to Note
① Even when breaking a word down does not reveal its exact meaning, it is often enough to identify only its part of speech and general value judgment (positive/negative/neutral). You can often follow the argument of the whole passage even without translating every word.
② Roots may change in spelling: duc/duct (introduce, conduct), mit/mis (permit, permission). Recognize these as variations of the same root.
③ Some prefixes do not have only one meaning: in- can mean “negation” (inactive) or “inside” (inside, invade). You must decide from the context.
④ This skill is a safety net that helps you read a sentence even when you do not know a word; it cannot replace memorizing vocabulary. The correct strategy is to memorize common words directly and use this skill for unfamiliar words.
- Guess the meaning of an unfamiliar word by breaking it into a prefix + root + suffix
- Grasp direction and degree in over-/under-/dis-/re-/inter-, and so on
- Build up knowledge of roots such as -spect/-duce/-tain/-vert/-sist
- In many cases, identifying the part of speech and value judgment is enough instead of translating perfectly
- Use guessing as a safety net, not as a substitute for memorization
Practice
- Explain the meaning of overreliance from its prefix.
- Break down underestimate from its prefix and guess its meaning.
- Name two words containing the root -tain and answer the meaning of each.