Prefixes

Prefixes are letters or groups of letters added to the beginning of a word to change its meaning. They help create new words and are essential for expanding vocabulary in business and everyday English.

• A prefix attaches to a base word (root) and modifies its meaning.
• Common functions: create opposites (un-, dis-), indicate repetition (re-), show time/position (pre-, sub-).
• Recognising prefixes helps you deduce the meaning of unfamiliar words in TOEIC reading/listening.

A prefix modifies the original word without changing its part of speech. Pay attention to small spelling changes and meaning differences.

• Attach a prefix to a base word: re + build = rebuild (verb stays a verb).
• Some prefixes create opposites (un-, dis-), others change nuance (pre-, inter-).
• Watch spelling: in- becomes im- before b, p, or m (e.g., impossible).

Prefixes change meaning but usually do not change the grammatical category of the base word.

Learners often make predictable errors when they form or interpret prefixed words. Watch for these universal pitfalls:

• Assuming every prefix simply makes the opposite — some change nuance, not exact antonyms.
• Creating double negatives by using a negative prefix and a negative word (e.g., 'not unhelpful').
• Spelling errors due to assimilation rules (in- → im- before b/p/m) or dropping letters incorrectly.
• Using the wrong prefix because several prefixes can produce similar meanings (e.g., un- vs dis-).
• Misreading the meaning of a prefixed word without checking the root (leads to wrong inference).

When in doubt, check a dictionary and pay attention to spelling and exact meaning.