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]