Is it ensure, insure, or assure?
1520s, "grotesque or comical gesture," from Italian antico "antique," from Latin antiquus "old" (see antique). Originally (like grotesque) a 16c. Italian word referring to the strange and fantastic representations on ancient murals unearthed around Rome (especially originally the Baths of Titus, rediscovered 16c.); later extended to "any bizarre thing or behavior," in which sense it first arrived in English. As an adjective in English from 1580s, "grotesque, bizarre."