any protuberant part; a round, swelling part or body; a knoblike process; as, a boss of wood.-a protuberant ornament on any work, either of different material from that of the work or of the same, as upon a buckler or bridle; a stud; a knob; the central projection of a shield. see umbilicus.-a projecting ornament placed at the intersection of the ribs of ceilings, whether vaulted or flat, and in other situations.-a wooden vessel for the mortar used in tiling or masonry, hung by a hook from the laths, or from the rounds of a ladder.-the enlarged part of a shaft, on which a wheel is keyed, or at the end, where it is coupled to another.-a swage or die used for shaping metals.-a head or reservoir of water.-to ornament with bosses; to stud.-a master workman or superintendent; a director or manager; a political dictator.