dimorphism

American  

[dahy-mawr-fiz-uhm] / daɪˈmɔr fɪz əm /

noun

1. Zoology. the occurrence of two forms distinct in structure, coloration, etc., among animals of the same species.

2. Botany. the occurrence of two different forms of flowers, leaves, etc., on the same plant or on different plants of the same species.

3. Crystallography. the property of some substances of crystallizing in two chemically identical but crystallographically distinct forms.

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dimorphism British  

/ daɪˈmɔːfɪzəm /

noun

1. the occurrence within a plant of two distinct forms of any part, such as the leaves of some aquatic plants

2. the occurrence in an animal or plant species of two distinct types of individual

3. a property of certain substances that enables them to exist in two distinct crystalline forms

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dimorphism Scientific  

/ dī-môr′fĭz′əm /

1. The existence of two distinct types of individual within a species, usually differing in one or more characteristics such as coloration, size, and shape. The most familiar type of dimorphism is sexual dimorphism, as in many birds (where the male is often more brightly colored than the female), spiders (where the male is often smaller than the female), horned and tusked mammals (where horns and tusks are often present in the male but not the female), and in some species of deep-sea anglerfish (where the male is reduced to a tiny parasitic form attached for life to the much larger female). Fungi also display dimorphism. For example, the same species may exist as a small, budding yeast under some conditions, but as a mass of long hyphae under others.

2. The occurrence, among plants, of two different forms of the same basic structure, either on the same plant or among individuals of the same species. The common ivy Hedera helix produces juvenile leaves with prominent lobes under conditions of low light, but adult leaves of more rounded shape under conditions of greater light.

3. The characteristic of a chemical compound to crystallize in two different forms. Potassium feldspar, for example, can crystallize as either orthoclase (at higher temperatures) or microcline (at lower temperatures).

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Other Word Forms

• dimorphic adjective

Etymology

Origin of dimorphism

First recorded in 1825–35; dimorph + -ism

Example Sentences

There are believed to be two ways in which sex chromosomes can cause sex-specific differences, also called sexual dimorphism, in cells.

From Salon • Apr. 22, 2025

The main groups in which the phenomenon has been recorded include animal species which feature strong sexual dimorphism; most often insects, especially butterflies, crustaceans, spiders, even lizards and rodents.

From Science Daily • Dec. 11, 2023

Modern humans have low sexual size dimorphism compared with the other great apes.

From Scientific American • Oct. 17, 2023

The hunt for genetic explanations above social linkages “reinforces the belief that … biological dimorphism drives a lot of illnesses,” she says.

From Science Magazine • Aug. 12, 2021

In insects with more than one brood in the year, seasonal dimorphism is often seen, and the differences are sometimes appropriate to the altered condition of the environment as the seasons change.

From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher" by Various