Source : Webster's Revised Unabridged Dictionary (1913)

Boss \Boss\ (b[o^]s; 115), n.; pl. {Bosses} (-[e^]z). [OE. boce,
   bose, boche, OF. boce, boche, bosse, F. bosse, of G. origin;
   cf. OHG. b[=o]zo tuft, bunch, OHG. b[=o]zan, MHG. b[^o]zen,
   to beat. See {Beat}, and cf. {Botch} a swelling.]
   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}.