In zoology, of one and the same (or essentially similar) type of structure; formed much alike; notably uniform in morphic character: said of a number of animals collectively, or of the zoölogical group which they constitute: as, birds are a highly monomorphic class of animals.In entomology, having but one form, structure, or morphological character; identical or invariable in form throughout successive stages of development; monomorphous; homomorphous; ametabolic.