dimorphism

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Biology The existence among animals of the same species of two distinct forms that differ in one or more characteristics, such as coloration, size, or shape.
2. n. Botany The occurrence of two distinct forms of the same parts in one plant, as in the juvenile and adult leaves of ivy.
3. n. Chemistry & Physics Dimorphic crystallization.

Century Dictionary and Cyclopedia

1. n. The property of assuming or of existing under two distinct forms. Specifically
2. n. In crystallography, the property of assuming two distinct crystalline forms not derivable from each other, as by crystallization. Thus, sulphur assumes one form when crystallizing at a high temperature, and another wholly different when becoming solid at the ordinary temperature. Hence, the same chemical substance may form two or more distinct mineral species. Carbon in one form is the diamond, in another graphite, etc.
3. n. In botany, the occurrence of two distinct forms of flowers or other parts upon the same plant, or upon plants of the same species.
4. n. In zoology, difference of form, structure, size, coloration, etc., between individuals of the same species. Sexual dimorphism is the rule in the animal kingdom; and differences between the male and female other than in the sexual organs, as well as constant differences between individuals of each sex, without reference to sex, are instances of dimorphism.
5. n. In philology, the existence of a word under two or more forms called doublets; thus, dent and dint, fat and vat, church and kirk, exhibit dimorphism developed within English, and card and chart, choir, quire, and chorus, reason, ration, ratio, etc., exhibit dimorphism arising outside of English.
6. n. In petrography, modifications produced within the magma of an igneous rock by mineralizing or crystallizing agents before its solidification.

Wiktionary

1. n. biology The occurrence within a plant of two distinct forms of any part.
2. n. biology The occurrence in an animal species of two distinct types of individual.
3. n. geology A property of certain substances that enables them to exist in two distinct crystalline forms.

GNU Webster's 1913

1. n. (Biol.) Difference of form between members of the same species, as when a plant has two kinds of flowers, both hermaphrodite (as in the partridge berry), or when there are two forms of one or both sexes of the same species of butterfly.
2. n. (Crystallog.) Crystallization in two independent forms of the same chemical compound, as of calcium carbonate as calcite and aragonite.

WordNet 3.0

1. n. (biology) the existence of two forms of individual within the same animal species (independent of sex differences)
2. n. (chemistry) the property of certain substances that enables them to exist in two distinct crystalline forms