To double; repeat; produce a second (like the first); make a copy or copies of.In physiology, to divide into two by natural growth or spontaneous division: as, some in-fusorians duplicate themselves.To become double; repeat or be repeated; specifically, in ecclesiastical use, to celebrate the mass or holy communion twice in the same day. See duplication.Double; twofold; consisting of or relating to a pair or pairs, or to two corresponding parts: as, duplicate spines in an insect; duplicate examples of an ancient coin; duplicate proportion.Consisting of a double number or quantity; multiplied by two.Exactly like or corresponding to something made or done before; repeating an original; matched: as, there are many duplicate copies of this picture; a duplicate action or proceeding.n. One of two or more things corresponding in every respect to each other.n. Specifically, in law and com.n. An instrument or writing corresponding in every particular to a first or original and of equal validity with it; an additional original.n. A second copy of a document, furnished by authority when the original has been lost, defaced, or invalidated.n. One of two or more things each of which corresponds in all essential respects to an original, type, or pattern; another corresponding to a first or original; another of the same kind; a copy: as, a duplicate of a bust.In whist and bridge, to play the same cards over again, as nearly as possible under the same conditions, each side getting the hands originally held by its opponents.In botany, folded.