Prefixes · Grade 3
A prefix is a group of letters added to the start of a word to change its meaning: happy → unhappy, write → rewrite. The spelling of the word itself never changes, so un- + necessary keeps both ns: unnecessary. Knowing what a prefix means helps you work out new words.
Key facts
- un-, dis-, in- mean not or the opposite: unkind, disagree, incorrect. Before a verb un- can mean undo: unlock, unpack.
- im- goes before m and p (impossible, immature), il- before l (illegal), ir- before r (irregular). All mean not.
- re- means again: rebuild, reread, refill.
- mis- means wrongly: misspell, misunderstand, misbehave.
- pre- means before: preview, preheat, prehistoric.
- Keep every letter: mis- + spell = misspell, il- + legal = illegal, ir- + regular = irregular.