Definition of "dimorphism" [di•mor•phism]

• 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. (noun)
• Botany The occurrence of two distinct forms of the same parts in one plant, as in the juvenile and adult leaves of ivy. (noun)
• Chemistry & Physics Dimorphic crystallization. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "In the case of the flower, where similar diversity of form occasionally exists, the term dimorphism is used."
• "The other possible explanation was sexual dimorphism, that is, size differences between males and females."
• "Some estimates put the rate of evolutionary change of sexual dimorphism, that is, trait differences between sexes, between 1 and 2 orders of magnitude slower than conventional population level evolution."