Boss n.; pl. Bosses
 1. Any protuberant part; a round, swelling part or body; a knoblike process; as, a boss of wood.
 2. 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.
 3. Arch. A projecting ornament placed at the intersection of the ribs of ceilings, whether vaulted or flat, and in other situations.
 4.  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.
 5. Mech. (a) The enlarged part of a shaft, on which a wheel is keyed, or at the end, where it is coupled to another. (b) A swage or die used for shaping metals.
 6. A head or reservoir of water. [Obs.]
 Bosses
    the projecting parts of a shield (Job 15:26). The Hebrew word
    thus rendered means anything convex or arched, and hence the
    back, as of animals.