antonyms

meaning in plain English

A word that means the opposite of another word.

Think of 'antonyms' as 'anti' (against) + 'onyms' (names) – words that fight each other's meanings.

for example

The word “antonyms” is in the sentence: “Hot and cold are antonyms because they mean opposite things.”

If you know what “happy” means, you can guess what “sad” means too—because they’re antonyms. Why do we need words that mean the opposite? So we can say things like, “I’m not tired,” instead of just “I’m awake.”