Janus \j(a)-nus\ as a boy's name is of Latin origin, and the meaning of Janus is "gateway". Janus was the Roman guardian of doors as well as of beginnings and endings. He had two faces, one of which looked forward and the other backward, and gave his name to the first month of the year, January. A Saint Januarius was martyred in the fourth century AD.

Janus has 9 variant forms: Gennadi, Gennaro, Janan, Janiusz, Januarius, Janusz, Jenaro, Jenarius and Jennaro.

Baby names that sound like Janus are Janos, Janse, Jens, Jonas, Jones and Junius.