pleomorphism

n. [ Gr. &unr_; more + morfh` form. ] 1. (Crystallog.) The property of crystallizing under two or more distinct fundamental forms, including dimorphism and trimorphism. [ 1913 Webster ]

2. (Biol.) The theory that the various genera of bacteria are phases or variations of growth of a number of Protean species, each of which may exhibit, according to undetermined conditions, all or some of the forms characteristic of the different genera and species. [ 1913 Webster ]