means A device for opening or closing an electrical circuit, or more broadly, the act of changing from one thing to another.

from First an English word for a thin, flexible riding-whip or twig (the kind that swishes through the air), likely borrowed from a Low German or Dutch source like 'swijch,' a bending branch. From the flick of that whippy stick came the verb to 'switch' — to flick, swap, or redirect — and when the 19th century needed a word for the little lever that flicks a train onto a new track, or current onto a new path, 'switch' was already waiting, ready to flip.