switch

Concise Oxford English Dictionary © 2008 Oxford University Press:
switch/swɪtʃ/

▶noun

• 1 a device for making and breaking an electrical connection.

  ■ Computing a program variable which activates or deactivates a function.

  ■ Computing a device which forwards data packets to an appropriate part of the network.

• 2 a change, especially a radical one.

• 3 a slender, flexible shoot cut from a tree.

• 4 N. Amer. a set of points on a railway track.

• 5 a tress of hair used in hairdressing to supplement a person's natural hair.

▶verb

• 1 change in position, direction, or focus.

  ■ exchange.

• 2 (switch something off/on) turn an electrical device off (or on).

  ■ (switch off) informal cease to pay attention.

• 3 archaic beat with or as if with a switch.

– derivatives
switchable adjective.

– origin C16 (denoting a thin tapering riding whip): prob. from Low Ger.