'Pleomorphism' definitions:

Definition of 'pleomorphism'

noun

(chemistry) the existence of different kinds of crystal of the same chemical compound [syn: polymorphism, pleomorphism]

noun

(biology) the appearance of two or more distinctly different forms in the life cycle of some organisms

From: GCIDE

Pleomorphism \Ple`o*mor"phism\, n. [Gr. ? 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]