Duplication. Definition. noun. (general) The act or process of duplicating; the state of being duplicated; a doubling. (biology) The state or act of dividing as a natural process of growth or a spontaneous action. (genetics) The act or process of duplicating or repeating a region in the genetic material or chromosome, as in gene duplication and chromosomal duplication. (pathology) A disorder in which a body part is duplicated, such as in diprosopus (a craniofacial duplication) and diphalia (a penile duplication). Supplement.