Prefixes

Prefixes are the fastest of the three word parts to use, because most of them do one job: they tell you whether the word is for or against, in or out, before or after. That is often all you need.

Negation and opposition

The group worth learning first.

One negation prefix flips the answer to the other side of the choices. If you know credulous means believing, then incredulous means disbelieving, and every positive choice can go.

The spelling changes

In- becomes im- before b, m and p, il- before l, and ir- before r. Impossible, illegal, irregular are the same prefix as inactive. Recognizing that saves you from treating them as four things.

Direction and position

In- appears twice in these tables, meaning "not" and meaning "into", and only the rest of the word tells you which. Inactive is not active; inject is to throw into. When a word starting with in- could go either way, check the root against both and see which makes a real word.

Time and sequence

Number and quantity

Reliable and easy, and the test uses them.

Degree and size

Hyper- and hypo- are opposites and are one letter apart, which is exactly the sort of pair a test writer puts in the same question. Hyper is high, and both start the same way.

Prefixes doing real work

Circumvent most nearly means

(A) confront (B) avoid (C) encircle (D) approve

Circum is around, vent is to come or go. To go around something.

(B) avoid. Note that (C) is the lookalike that uses only the prefix, and (A) is the opposite - going through rather than around.

Antipathy most nearly means

(A) sympathy (B) dislike (C) enthusiasm (D) indifference

Anti is against, path is feeling. Feeling against.

(B) dislike. (A) is the same root with the opposite prefix, which is a trap you can see coming once you know the prefix. (D) is closer than it looks - indifference is the absence of feeling rather than feeling against - which is why "most nearly" still needs the better of the two.

Unwitting most nearly means

(A) deliberate (B) unaware (C) humorless (D) foolish

Un- is not, and witting relates to knowing. Not knowing.

(B) unaware. (C) is the trap for anyone reading "wit" as humor rather than as knowledge, and (A) is the opposite.

What you can skip

• Rare prefixes. About 266 of the tested words start with one of the common prefixes in this lesson; the value is in those, not in a long list of unusual ones.

Where people lose points

Assuming every word-initial prefix is a prefix. Invaluable, inflammable, indifferent.

Missing that in- has two meanings.

Confusing hyper- and hypo-.

Using the prefix and ignoring the root, which produces the lookalike answer. "Encircle" for circumvent.

Forgetting the spelling shifts, and treating irrational as unrelated to inactive.

Work one in under a minute

The general's decision was unilateral.

(A) agreed by all parties (B) made by one side alone (C) delayed (D) reversed

Uni is one, lateral relates to side. One-sided.

(B) made by one side alone. (A) is the opposite and is what multilateral would mean, which is the trap built by swapping the prefix on the same root.

Where this leads

Prefix, root and suffix are one method. The prefix is the piece that most often decides between two surviving choices, because it sets direction.