As a Noun: 1. A thing which is completely different from another thing of the same kind in one particular way. English = opposite. 2. Of signs and words, to be a word or sign which is completely different in meaning from another word or sign in one particular way. English = opposite, antonym. 3. In mathematics, the negative of a number; numbers that, when added, the answer is zero. English = opposite. As a Verb or Adjective: 1. Of two things, for one to be located on the other side of a space from the other thing. English = (be) opposite. 2. Of two things or qualities, to be as different as possible from each other in a particular way. For example, north and south, or win and lose, or good and bad. English = (be) opposite.