melanism
noun
mel·a·nism ˈme-lə-ˌni-zəm 
1
: an increased amount of black or nearly black pigmentation (as of skin, feathers, or hair) of an individual or kind of organism compare industrial melanism
2
: intense human pigmentation of the skin, eyes, and hair
melanistic
ˌme-lə-ˈni-stik
adjective 
Example Sentences
Recent Examples on the Web To determine the origins of squirrel melanism, or dark coloration, McRobie and colleagues from Cambridge University and the Virginia Museum of Natural History extracted DNA from gray and fox squirrel specimens found in North America. 
Meilan Solly, Smithsonian, 16 Aug. 2019 But why melanism evolved in cats is a trickier question. Sergio Pitamitz, National Geographic, 22 Mar. 2017 The animal is melanistic—its genes carry a mutation that creates more dark pigment than light pigment, according to Eduardo Eizirik, a biologist and cat-melanism expert at Pontifical Catholic University of Rio Grande do Sul in Brazil. Sergio Pitamitz, National Geographic, 22 Mar. 2017
Meilan Solly, Smithsonian, 16 Aug. 2019 But why melanism evolved in cats is a trickier question. Sergio Pitamitz, National Geographic, 22 Mar. 2017 The animal is melanistic—its genes carry a mutation that creates more dark pigment than light pigment, according to Eduardo Eizirik, a biologist and cat-melanism expert at Pontifical Catholic University of Rio Grande do Sul in Brazil. Sergio Pitamitz, National Geographic, 22 Mar. 2017 Word History
Etymology
borrowed from French mélanisme, from Greek melan-, stem of mélās "black, dark" + French -isme -ism, on the model of albinisme albinism — more at melano-
Note: French mélanisme appears in the 1820's, perhaps earliest in De l'organisation des animaux, ou Principes d'anatomie comparée, tome premier (Paris, 1822), by the zoologist Henri Marie Ducrotay de Blainville (1777-1850).
First Known Use
1843, in the meaning defined at sense 1
Phrases Containing melanism
Medical Definition
melanism
noun
mel·a·nism ˈmel-ə-ˌniz-əm
1
: an increased amount of black or nearly black pigmentation (as of skin, feathers, or hair) of an individual or kind of organism
2
: intense human pigmentation in skin, eyes, and hair