Pronunciation: (pol"ē-môr'fiz-um),[key] —n. 1. the state or condition of being polymorphous.
2. Crystall.crystallization into two or more chemically identical but crystallographically distinct forms.
3. Biol.the existence of an organism in several form or color varieties.
4. Genetics.the presence of two or more distinct phenotypes in a population due to the expression of different alleles of a given gene, as human blood groups O, A, B, and AB.