countershading
noun
coun·ter·shad·ing ˈkau̇n-tər-ˌshā-diŋ 
: cryptic coloration of an animal with parts normally in shadow being light and parts normally illuminated being dark thereby reducing shadows and contours
Example Sentences
Recent Examples on the Web The latter, which is most common, features a pattern called countershading, in which the fish has a black back and a white belly. 
National Geographic, 11 Feb. 2020 The study of fossilized pigments has continued to expose new information about prehistoric life, hinting at potential animal survival strategies by showing evidence of countershading and camouflage. Jay Bennett, Smithsonian Magazine, 6 May 2012 Tree kangaroos show countershading, Holtz says, and the forest-dwelling raccoon dogs wear color patterns much like Sinosauropteryx. Brian Switek, Smithsonian, 26 Oct. 2017 Modern-day predators rely on an object’s shading to assess its shape, Vinther explains, and when prey is darker on top than on the bottom, a color scheme known as countershading, shadows are minimized and the animals look flatter. National Geographic, 14 Sep. 2016 A beautifully colored dinosaur fossil is the first to show evidence of countershading, a type of camouflage. National Geographic, 14 Sep. 2016
National Geographic, 11 Feb. 2020 The study of fossilized pigments has continued to expose new information about prehistoric life, hinting at potential animal survival strategies by showing evidence of countershading and camouflage. Jay Bennett, Smithsonian Magazine, 6 May 2012 Tree kangaroos show countershading, Holtz says, and the forest-dwelling raccoon dogs wear color patterns much like Sinosauropteryx. Brian Switek, Smithsonian, 26 Oct. 2017 Modern-day predators rely on an object’s shading to assess its shape, Vinther explains, and when prey is darker on top than on the bottom, a color scheme known as countershading, shadows are minimized and the animals look flatter. National Geographic, 14 Sep. 2016 A beautifully colored dinosaur fossil is the first to show evidence of countershading, a type of camouflage. National Geographic, 14 Sep. 2016 Word History
First Known Use
1896, in the meaning defined above