n. One who sails; a seaman; a mariner; one of the crew of a ship or vessel.n. Synonyms Sailor, Seaman, Mariner. To most landsmen any one who leads a seafaring life is a sailor. Nelson was a great sailor. Technically, sailor applies only to the men before the mast. To a landsman seaman seems a business term for a sailor; technically, seaman includes sailors and petty officers. Mariner is an elevated, poetic, or quaint term for a seaman; shipman is a still older term. The technical use of mariner is now restricted to legal documents. There is no present distinction in name between the men in the navy and those in the merchant marine.