■ noun
1》 a short plastic or wooden rod attached to one side of a garment, pushed through a loop on the other side to act as a fastener.
↘a pin or other crosspiece put through the eye of a rope or a link of a chain to keep it in place.
↘(also ~ bolt ) a wall fastener for use on open-backed plasterboard, having a part that springs open or turns through 90° after it is inserted.
2》 Computing a key or command that is operated the same way but with opposite effect on successive occasions.
■ verb
1》 Computing switch from one effect, feature, or state to another with a ~.
2》 provide or fasten with a ~ or ~s.
Origin
C18 (orig. in naut. use): of unknown origin.