sex·u·al di·mor·phism / sex.shoe.al die.more.fizm
noun – when male and female of a species are different in size and/or appearance.
related forms of sexual dimorphism: sexually dimorphic (displaying sexual dimorphism)
sexual dimorphism in a sentence: many birds are sexually dimorphic; the males are typically much more colorful than the females.
examples of sexual dimorphism in nature: orchid mantises, mandarin duck (most birds, in fact), frigatebirds, most deer, Goliath beetles, lions, mandrills, emerald tree boas, pheasants, even people!