adjective: having two contrasting aspects; especially : duplicitous, two-faced
The dancers wore grotesque Janus-faced masks, flashing faces of terror and pleasure as they twirled about the stage.
“The helmsman decreased speed a fraction, steering the boat to mid-river. The surface was glassy and the reflections of the trees made it difficult to tell up from down. A Janus-faced river, Harry thought.” — Ward Just, American Romantic, 2014
Did you know?
In Roman religion, Janus was the deity who presided over doors, gates, archways, and all beginnings, structural and temporal (the month of January is named for him). He is represented as having a single head with two faces looking in opposite directions. The shrine of Janus in the Roman Forum was a rectangular bronze structure with double doors at each end. Traditionally, the doors were left open in times of war and kept closed in times of peace. That open/closed dichotomy, along with the deity’s two-faced head, confers duplicity and contrariness to the word “Janus,” evinced in the meaning of the term “Janus-faced.”