a person skilled in seamanship.

a person whose trade or occupation is assisting in the handling, sailing, and navigating of a ship during a voyage, esp. one below the rank of officer; sailor.

U.S. Navy and Coast Guard . an enlisted person ranking below petty officer.

noun

jack , jack-tar , mariner , navigator , sea dog , seafarer , beachcomber , cockswain , gob , jacky , mate , merman , middy , midshipman , pilot , sailor , salt , skipper , tar , tarpaulin