Switch  —n. 1 device for completing and breaking an electric circuit. 2 a transfer, change-over, or deviation. B exchange. 3 flexible shoot cut from a tree. 4 light tapering rod. 5 us railway points. —v. 1 (foll. By on, off) turn (an electrical device) on or off. 2 change or transfer. 3 exchange. 4 whip or flick with a switch.  switch off colloq. Cease to pay attention. [low german]