A three-legged machine fitted with a windlass, heaving in the fall from a purchase-block at the summit, much used on shore for mounting and dismounting guns, driving piles, &c. (See gibraltar gyn.)
·vi To begin [Obs.] ·see <<Gin>>. ...
Webster's Dictionary of the English Language
Originally devised there for working guns under a low roof. (See gyn.) ...
The Sailor's Word-Book