n.
Roman god of doorways and archways, after whom the month of January is named.
Often depicted as a double-faced head, he was a deity of beginnings. The worship of Janus dated back to the earliest years of Rome, and the city had many freestanding ceremonial gateways called jani , used for symbolically auspicious entrances or exits. The most famous was the Janus Geminus, whose double doors were left open in time of war and closed when Rome was at peace. The festival of Janus, the Agonium, took place on January 9.
The god Janus, beardless, Roman coin; in the Bibliothèque Nationale, Paris
Larousse