n A wooden pin tapering toward both ends with a groove around its middle, fixed transversely in the eye of a rope to be secured to any other loop, ring, or bight.
n A kind of button or frog capable of being readily engaged and disengaged for temporary purposes.
n (nautical) A wooden or metal pin, short rod, crosspiece or similar used for securing a loop in a rope or chain, etc. (often temporarily) to another, e.g. a sea painter to a lifeboat. (FM 55-501)
n A toggle switch; a switch, usually with two positions, activated by a lever; an on/off switch.
n (context|Scouting) A circle of leather, plastic (Cub Scouts) etc, resembling a napkin holder to keep the neckerchief in place.