switcher

noun

1. One who or that which operates a switch.

   “They all love frugality and conservation; they are manic savers of bits of string and switchers-off of lights.”

2. One who or that which switches, that is, changes in some way.

   “career switcher”

   “Switch to Acme brand razors for a closer shave! For a limited time, we'll pay you to be a switcher!”

   “As a career switcher, I diligently attended all the company presentations on campus, and quickly settled on sales and trading. My prior position was in hospital sales.”

   “In short, the task switcher gives you a way to jump directly to another app, without a layover at the Home screen first.”

3. A switchmode power supply.
4. (US)A railway locomotive used for shunting (switching).
5. (US)The yardman who operates such an engine, or performs a similar role in a trucking depot.
6. Synonym of vision mixer (“device for selecting between video sources”).