hideous (adj.)
c.1300, "terrifying, horrible, dreadful," from Anglo-French hidous, Old French hideus, earlier hisdos "hideous, horrible, awful, frightening" (11c.; Modern French hideux), from hisda "horror, fear," perhaps of Germanic origin; or else from Vulgar Latin *hispidosus, from Latin hispidus "shaggy, bristly," "[b]ut this presents numerous difficulties" [OED]. Meaning "repulsive" is late 14c.