Meaning

noun any instruction that works first one way and then the other; it turns something on the first time it is used and then turns it off the next time

noun a hinged switch that can assume either of two positions

noun a fastener consisting of a peg or pin or crosspiece that is inserted into an eye at the end of a rope or a chain or a cable in order to fasten it to something (as another rope or chain or cable)

originOf uncertain origin. Possible alteration of tug (“to pull”) + -le

Etymology from Wiktionary, CC BY-SA 3.0