noun

1. Bot. the state of having two different kinds of leaves, flowers, stamens, etc. on the same plant or in the same species
2. Mineralogy the property of crystallizing in two forms
3. Zool. the occurrence of two types of individuals in the same species, distinct in coloring, size, etc.

Etymology: < Gr dimorphos, having two forms (< di-, two + morphē, form) + -ism