ancient Italic deity, guardian god of portals, doors, and gates; patron of beginnings and endings, c.1500, from Latin Ianus, literally "gate, arched passageway," perhaps from PIE root *ei- (1) "to go" (cognates: Sanskrit yanah "path," Old Church Slavonic jado "to travel"). He is shown as having two faces, one in front the other in back. His temple in Rome was closed only in times of peace.