What a prefix does
A prefix is added to the beginning of a base word. It usually changes meaning while leaving the word class unchanged: possible and impossible are both adjectives; write and rewrite are both verbs.
High-value meaning groups
- Negative or opposite: un- (unfair), in-/im-/il-/ir- (inaccurate, impossible, illegal, irregular), non- (nonverbal).
- Again or back: re- (reconsider, return).
- Before and after: pre- (preoperative), post- (postgraduate).
- Degree or size: over- (overestimate), under- (underfunded), mini- and micro-.
- Number: mono-, bi-, tri-, multi-.
Spelling and meaning cautions
The negative prefix changes form to match the following sound: in- becomes im- before many words beginning with m or p, il- before l, and ir- before r. A familiar-looking beginning is not always a prefix: the re in real does not mean again.
Reading strategy
When you meet an unfamiliar word, remove a recognizable prefix, identify the base, combine the meanings, and then verify the result in context. For underrepresentation, the pieces suggest insufficient representation. The surrounding paragraph tells you what or whom is represented too little.
Quick practice
Choose a prefix to complete each word: ___legal, ___estimate, ___write, ___lingual. Possible answers are illegal, underestimate or overestimate depending on context, rewrite, and multilingual.