Antonym definition: a word opposite in meaning to another. Fast is an antonym of slow.. See examples of ANTONYM used in a sentence. A word that has the exact opposite meaning of another word is its antonym. Life is full of antonyms, from the "stop" and "go" of a traffic signal to side-by-side restroom doors labeled "men" and "women." Opposites – Created by 7ESL Antonyms are basically just words with opposite meanings to one another. Conversely, synonyms are words with meanings that are the same as one another. Most people don’t know that there are, in fact, different types of antonyms though. Below we’ll take a look at these different types of antonyms, explain what they are, and provide some examples to make it clearer. Antonyms (opposites) examples: Night – Day Arrive – Leave Junior – Senior Better ... Define antonym. antonym synonyms, antonym pronunciation, antonym translation, English dictionary definition of antonym. n. A word having a meaning opposite to that of another word: The word "wet" is an antonym of the word "dry." an′to·nym′ic adj. an·ton′y·mous adj....