1640s, "one who schemes or plots;" agent noun from design (v.). In manufacturing or the fine arts, "one who makes an artistic design or a construction plan" is from 1660s. In fashion, as an adjective, "bearing the label of a famous clothing designer" (thus presumed to be expensive or prestigious), from 1966. Designer drug, one that mimics an illegal narcotic but has a different chemical composition so as to avoid legal restrictions, is attested by 1983.
