"one afflicted with leprosy," 1387, from L.L. lepra, from Gk. lepra "leprosy," from fem. of lepros (adj.) "scaly," from leops "a scale," related to lepein "to peel," from lopos "a peel," from PIE base *lep- "to peel, scale" (see leaf). Originally the word for the disease itself (c.1250); because of the -er ending it came to mean "person with leprosy," so leprosy was coined 16c. from adj. leprous.