1switch 
/ˈswɪtʃ/ noun
plural switch·es /ˈswɪtʃ/ noun [count] 1 : a small device that starts or stops the flow of electricity to something (such as a lamp or a machine) when it is pressed or moved up and down
▪ She flicked a switch and turned the lamp/lights on. ▪ a light/dimmer switch ▪ He threw the switch to stop the machine. — see also dip switch, toggle switch 2 : a sudden change from one thing to another — usually singular ▪ a switch from the old way of doing things ▪ There has been a switch in plans. [=the plans have changed] ▪ If you're not happy in your current job, maybe it's time to make a switch (to another job). ▪ “He says he'll do it himself.” “Well, that's a switch.” [=that's something unusual] — see also bait and switch 3 US : a device for moving the rails of a track so that a train may be turned from one track to another 4 : a thin stick that can be easily bent
▪ She flicked a switch and turned the lamp/lights on. ▪ a light/dimmer switch ▪ He threw the switch to stop the machine. — see also dip switch, toggle switch
