Old English beacen "sign, portent, lighthouse," from West Germanic *baukna "beacon, signal" (cognates: Old Frisian baken, Old Saxon bokan, Old High German bouhhan); not found outside Germanic. Perhaps borrowed from Latin bucina "a crooked horn or trumpet, signal horn." But more likely from PIE *bhew-, a variant of the base *bha- (1) "to gleam, shine" (see phantasm). Figurative use from c.1600.