Real Dictionary

switch
countable noun: A switch is a small control for an electrical device which you use to turn the device on or off.
verb: If you switch to something different, for example to a different system, task, or subject of conversation, you change to it from what you were doing or saying before.
verb: If you switch your attention from one thing to another or if your attention switches, you stop paying attention to the first thing and start paying attention to the second.

switch in American English
a thin, flexible twig, rod, stick, etc., esp. one used for whipping
to whip or beat with or as with a switch
noun: a slender, flexible shoot, rod, etc., used esp. in whipping or disciplining

switch in British English
noun: a mechanical, electrical, electronic, or optical device for opening or closing a circuit or for diverting energy from one part of a circuit to another

switch in Electrical Engineering 1
noun: A switch is a mechanical, electrical, electronic, or optical device for opening or closing a circuit or for diverting energy from one part of a circuit to another.

switch in Electrical Engineering 2
verb: If you switch an electric current on or off, you cause it to start or stop flowing or to change its path by operating a switch.