n. The act of duplicating, or of making or repeating something essentially the same as something previously existing or done.n. In arithmetic, the multiplication of a number by two.n. A folding; a doubling; also, a fold: as”, the duplication of a membrane.n. In physiology, the act or process of dividing into two by natural growth or spontaneous division.n. In music, the process or act of adding the upper or lower octaves or replicates to the tones of a melody or harmony. See double, n. and verbn. In botany, same as chorisis.n. In admiralty law, a pleading on the part of the defendant in reply to the replication.n. Eccles., the celebration of the mass or eucharist twice by the same priest on the same day.