The Collaborative International Dictionary of English v.0.48:

Nib \Nib\ (n[i^]b), n. [A variabt of neb.]
   1. A small and pointed thing or part; a point; a prong. "The
      little nib or fructifying principle." --Sir T. Browne.
      [1913 Webster]

   2. (Zool.) The bill or beak of a bird; the neb.
      [1913 Webster]

   3. The points of a pen; also, the pointed part of a pen; a
      short pen adapted for insertion in a holder.
      [1913 Webster]

   4. One of the handles which project from a scythe snath;
      also, [Prov. Eng.], the shaft of a wagon.
      [1913 Webster]

   5. pl. See his nibs, below.
      [PJC]

   his nibs Someone who gives a command or makes a demand,
      often one who acts in a self-important manner, sometimes
      one with authority; -- used mockingly as a jocose term, as
      if a title of honor, but not usually in the presence of
      the person referred to, and usually indicating resentment
      or contempt. [Colloq.]
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Nib \Nib\, v. t. [imp. & p. p. Nebbed; p. pr. & vb. n.
   Nibbing.]
   To furnish with a nib; to point; to mend the point of; as, to
   nib a pen.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Neb \Neb\ (n[e^]b), n. [AS. nebb head, face; akin to D. neb,
   Icel. nef, beak of a bird, nose, Dan. naeb beak, bill, Sw.
   n[aum]bb, n[aum]f, and prob. also to D. sneb, snavel, bill,
   beak, G. schnabel, Dan. & Sw. snabel, and E. snap. Cf. Nib,
   Snap, Snaffle.]
   The nose; the snout; the mouth; the beak of a bird; a nib, as
   of a pen. [Also written nib.] --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nib
    n 1: the writing point of a pen [syn: nib, pen nib]
    2: horny projecting mouth of a bird [syn: beak, bill, neb,
       nib, pecker]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "nib":
   Thule, Ultima Thule, aculeus, acumination, antlia, auger, beak,
   beezer, bill, bit, bitter end, borer, bottom dollar, boundary,
   bugle, butt, butt end, conk, cusp, drill, extreme, extremity,
   fag end, farthest bound, jumping-off place, limit, mucro, muffle,
   muzzle, nares, neb, needle, nose, nostrils, nozzle,
   olfactory organ, pecker, point, pole, prick, prickle, proboscis,
   rhinarium, rostrum, schnozzle, smeller, snoot, snout, sting, stub,
   stump, tag, tag end, tail, tail end, tip, trunk