Vocabulary & Word Structure-Decoding Words: Prefixes, Suffixes & Root Words
Decoding Words
Prefixes, Suffixes & Root Words (Etymology)
Suggested Video: What are Prefixes and Suffixes?
Objective
Students will learn to decode unfamiliar words by breaking them into morphemes (roots, prefixes, suffixes) to infer meaning quickly and accurately on MCQ vocabulary and comprehension items.
Part I — The Three Building Blocks of English Words
Etymology studies word origins; for tests we focus on morphology — the structure of words. Most academic words can be analyzed using three components:
| Word Part | Definition | Function | Examples |
|---|---|---|---|
| Root | Core part carrying the primary meaning. | May or may not stand alone. | vis (see), struct (build), geo (earth) |
| Prefix | Added to the beginning of a root. | Modifies word meaning. | pre- (before), un- (not), sub- (under) |
| Suffix | Added to the end of a root. | Often changes part of speech. | -tion (noun), -able (adj), -ly (adv) |
Nearly 60–70% of higher-level English vocabulary derives from Latin/Greek; learning morphemes is a high-return study tactic.
Part II — Deep Dive into High-Utility Word Parts
A. Essential Latin & Greek Roots
A short list of high-frequency roots you should master.
| Root | Meaning | Example | Breakdown |
|---|---|---|---|
| VID / VIS | to see | Visible | vis (see) + -ible (able to) = able to be seen |
| DICT | to say | Predict | pre- (before) + dict (say) = say before (foretell) |
| SCRIPT / SCRIB | to write | Inscribe | in- (in) + scrib (write) = to write into |
| TRACT | to pull | Extract | ex- (out) + tract (pull) = pull out |
| DUC / DUCT | to lead | Conductor | con- (with) + duct (lead) = one who leads |
| FLECT / FLEX | to bend | Reflect | re- (back) + flect (bend) = bend back |
B. High-Impact Prefixes
Prefixes often determine the direction, negation or scale of a word.
Negative
un-, in-, im-, dis-, non-, a- — not / opposite of
Examples: Incomplete, Disagree, Amoral
Number
uni-, bi-, tri-, multi- — one, two, three, many
Examples: Unicycle, Bilingual, Triangle
Time / Order
pre-, post-, re- — before, after, again
Examples: Preview, Postpone, Reorganize
Location
sub-, super-, inter-, trans- — under, over, between, across
Examples: Submarine, Supersonic, Interact
C. Suffixes That Reveal Part of Speech
Suffixes help identify whether a word is a noun, adjective, verb or adverb.
| Part of Speech | Common Suffixes | Examples |
|---|---|---|
| Noun | -tion, -sion, -ment, -ity, -ness, -ence | Adoption, Decision, Movement, Clarity, Kindness |
| Adjective | -ous, -able, -ible, -al, -ic, -ful | Spacious, Incredible, Global, Harmful |
| Adverb | -ly | Quickly, Gently |
| Verb | -ate, -ify, -ize, -en | Complicate, Simplify, Finalize, Widen |
Part III — Strategy for the Test (MCQ Focus)
- Identify the root: What is the core meaning? (e.g., spect = look)
- Identify the prefix: Does it add negation, direction, or number? (e.g., in- meaning into)
- Identify the suffix: What is the part of speech? (e.g., -tion = noun)
- Predict & Verify: Combine parts and match to the best answer choice.
Quick elimination tip: negative prefixes (un-, dis-, im-) allow fast removal of positively-toned options.
Part IV — Practice Tasks
Task 1 — Break Down & Define
Break each word into prefix + root + suffix and write the meaning:
- Subterranean
- Interject
- Reversible
Task 2 — Part-of-Speech Swap
Using the root sens (to feel/know), form:
- Noun: sensation
- Adjective: sensitive
- Adverb: sensitively
Task 3 — MCQ Practice
Given malleable (-able = capable of), choose the most likely meaning:
- Easy to confuse
- Able to be shaped (correct)
- Made of metal
- Not required
Task 4 — Create Opposites
Add a negative prefix to form opposites:
- legible → illegible
- rational → irrational
- obey → disobey