Ja‧nus /ˈdʒeɪnəs/
in Roman mythology, the god of gates and doorways and of new beginnings. Janus is usually shown in pictures with two faces, one of which looks back at the past while the other looks forward towards the future. The expression ‘Janus-faced’ is a literary way of describing someone who is two-faced (=they change what they say according to who they are talking to, in an insincere and unpleasant way).

[TahlilGaran] Dictionary of Contemporary English ▲