INVERSE

I. adjective Etymology: Middle English, turned upside down, from Latin inversus, from past participle of invertere Date: 15th century opposite in order, nature, or effect, being an ~ function , II. noun Date: circa 1681 something of a contrary nature or quality ; opposite , reverse , a proposition or theorem formed by contradicting both the subject and predicate or both the hypothesis and conclusion of a given proposition or theorem , 3. ~ function , a set element that is related to another element in such a way that the result of applying a given binary operation to them is an identity element of the set