(of the conspicuous coloration of certain animals) acting as a warning, esp to potential predators
Word Origin
C19: from Greek sēma a sign
Word Origin and History for sematic
adj.
"significant, indicative," 1890, from Greek semat-, comb. form of sema (genitive sematos) "sign" (see semantic) + -ic. Used especially in biology, in reference to "warning" colors, etc.