Janus was a Roman god with two faces; one looking forward and the other looking back.
Janus | Doppler effect | Mass Effect | Janus (mythology) | Special effect | Mass Effect 3 | Magnus effect | Venturi effect | Mössbauer effect | Hall effect | sound effect | Mass Effect 2 | Kondo effect | Hall effect sensor | Bandwagon effect | The Effect of Gamma Rays on Man-in-the-Moon Marigolds | The Butterfly Effect | Karma and Effect | Janus Metz Pedersen | Janus kinase 1 | Coriolis effect | Chorus effect | Zeeman effect | Wiegand effect | Tyndall effect | Triboelectric effect | Stroop effect | spoiler effect | Sound effect | Reggie and the Full Effect |