🔤 Roots, Prefixes and Suffixes

Part 1 of 7 — How Word Parts Unlock Meaning

Topic Overview

Why Word Parts Matter on Word Knowledge

Word Knowledge (WK) gives you 15 questions in 9 minutes on the CAT-ASVAB, about 36 seconds each. Many questions show a word alone, with no sentence to help: "Malfunction most nearly means ___." When there is no context, the word itself is the only clue you have.

That is where word parts come in. Most longer English words are built from smaller pieces borrowed from Latin and Greek. A few dozen of those pieces show up in thousands of words. Learn the pieces once and you can take apart words you have never seen.

And WK is worth the effort. Your AFQT sum is AR + MK + 2 × VE, where VE is a weighted blend of Word Knowledge and Paragraph Comprehension (WK counting more). Verbal skill is half of the AFQT sum.

The Three Kinds of Parts

A word can have more than one prefix or suffix, and some words are just a root plus a suffix.

🔤 Roots, Prefixes and Suffixes

Part 2 of 7 — Prefixes That Change Meaning

Prefixes That Mean "Not" or "Against"

These are the most valuable prefixes on the test, because they flip a word. If you know the base word, the prefix hands you the opposite.

Spelling note: in- changes to im- before b, m and p (impolite), to il- before l (illegal) and to ir- before r (irregular). All four mean the same thing.

Prefixes of Time and Place

Key Fact: A prefix on a word you know gives you the answer almost for free. Un- + steady = not steady. Look for a familiar word hiding behind the prefix.

🔤 Roots, Prefixes and Suffixes

Part 3 of 7 — Latin Roots

The Core of the Word

The root carries the main meaning. Latin roots are the backbone of formal English, the kind of words that show up in regulations, news reports and the ASVAB. Here are the families worth knowing cold:

Key Fact: You already know at least one word in almost every family: tractor (pulls), eject (throws out), erupt (breaks out). Use the word you know to unlock the word you don't.

🔤 Roots, Prefixes and Suffixes

Part 4 of 7 — Greek Roots and Number Parts

Greek Roots

Greek roots fill the vocabulary of science, medicine and technology. Many of them are already in words you use every day.

Number Parts

Key Fact: Many Greek words are two roots glued together: tele + scope (far + look), auto + graph (self + write), geo + logy (earth + study). Translate each half and the meaning appears.

🔤 Roots, Prefixes and Suffixes

Part 5 of 7 — Suffixes and Parts of Speech

What a Suffix Tells You

A suffix sits at the end of a word and usually tells you its part of speech: is it a thing (noun), an action (verb) or a description (adjective)? That matters on Word Knowledge because the right answer is always the same part of speech as the test word. A noun's synonym is a noun; an action's synonym is an action.

Suffixes That Add Meaning

A few suffixes do more than set the part of speech:

Key Fact: Check the ending of the test word and the endings of the choices. A choice in the wrong part of speech can be eliminated even if you have no idea what the word means.

🔤 Roots, Prefixes and Suffixes

Part 6 of 7 — Test Strategy and Common Traps

Word Parts on the Clock

You have about 36 seconds per Word Knowledge question on the CAT-ASVAB (15 questions in 9 minutes). Word parts are fast when you use them as a shortcut, not as a research project.

You cannot return to an answered question on the CAT, and you must answer to move on. Unanswered questions at the time limit are scored as random guesses, and a run of wrong answers at the very end of a subtest carries a relatively large penalty, so do not get stuck dissecting one word.

Trap 1: The Prefix That Is Not "Not"

In- usually means not, but it can also mean in or into:

And a few words are famous for fooling people:

• Inflammable means easily set on fire, the same as flammable. (The in- here means into, as in bursting into flame.) A truck marked INFLAMMABLE is dangerous, not safe.
• Invaluable means priceless, so valuable it cannot be measured, not "worthless."
• Infamous means famous for something bad, not "unknown."

Trap 2: Letters That Only Look Like a Root

Not every "port" is a root. Portion (a share) and portrait (a picture of a person) have nothing to do with carrying. Pressure contains pre, but it does not mean "before." If a split gives you nonsense, drop it and use another strategy.

Trap 3: Trusting a Root Too Far

A root gives a direction, not a definition. Submarine and substantial both start with sub, but substantial means large or considerable, nothing to do with being under anything. Use the root to rule out choices that point the wrong way, then choose the best fit among what is left.

🔤 Roots, Prefixes and Suffixes

Part 7 of 7 — Mixed Mastery Set

How to Use This Set

Eleven questions that mix every kind of word part, in both Word Knowledge formats. Work them at test speed: about 36 seconds each, so roughly 6 to 7 minutes for the set.

For each word:

1. Know it? Answer and move on.
2. Split it into prefix, root and suffix.
3. Translate and build a rough meaning.
4. Eliminate choices that point the wrong way or are the wrong part of speech.
5. Watch the traps: in- meaning into, letters that only look like a root, look-alike words.

Quick Reference