Source : Webster's Revised Unabridged Dictionary (1913)

Bump \Bump\, v. i. [See {Boom} to roar.]
   To make a loud, heavy, or hollow noise, as the bittern; to
   boom.

         As a bittern bumps within a reed.        --Dryden.

Bump \Bump\, n.
   The noise made by the bittern.

Bump \Bump\, v. t. [imp. & p. p. {Bumped}; p. pr. & vb. n.
   {Bumping}.] [Cf. W. pwmp round mass, pwmpiaw to thump, bang,
   and E. bum, v. i., boom to roar.]
   To strike, as with or against anything large or solid; to
   thump; as, to bump the head against a wall.

Bump \Bump\, v. i.
   To come in violent contact with something; to thump.
   ``Bumping and jumping.'' --Southey.

Bump \Bump\, n. [From {Bump} to strike, to thump.]
   1. A thump; a heavy blow.

   2. A swelling or prominence, resulting from a bump or blow; a
      protuberance.

            It had upon its brow A bump as big as a young
            cockerel's stone.                     --Shak.

   3. (Phren.) One of the protuberances on the cranium which are
      associated with distinct faculties or affections of the
      mind; as, the bump of ``veneration;'' the bump of
      ``acquisitiveness.'' [Colloq.]

   4. The act of striking the stern of the boat in advance with
      the prow of the boat following. [Eng.]

Source : WordNet®

bump
     n 1: a lump on the body caused by a blow
     2: something that bulges out or is protuberant or projects from
        a form [syn: {bulge}, {hump}, {gibbosity}, {gibbousness},
        {jut}, {prominence}, {protuberance}, {protrusion}, {extrusion},
         {excrescence}]
     3: an impact (as from a collision); "the bump threw him off the
        bicycle" [syn: {blow}]

bump
     v 1: knock against with force or violence; "My car bumped into
          the tree" [syn: {knock}]
     2: come upon, as if by accident; meet with; "We find this idea
        in Plato"; "I happened upon the most wonderful bakery not
        very far from here"; "She chanced upon an interesting book
        in the bookstore the other day" [syn: {find}, {happen}, {chance},
         {encounter}]
     3: dance erotically or dance with the pelvis thrust forward;
        "bump and grind"
     4: assign to a lower position; reduce in rank; "She was demoted
        because she always speaks up"; "He was broken down to
        Sargeant" [syn: {demote}, {relegate}, {break}, {kick
        downstairs}] [ant: {promote}]
     5: remove or force from a position of dwelling previously
        occupied; "The new employee dislodged her by moving into
        her office space" [syn: {dislodge}, {displace}]

Source : Free On-Line Dictionary of Computing

bump
     
        Increment.  E.g. {C}'s {++} operator.  It is used especially of
        counter variables, pointers and index dummies in "for",
        "while", and "do-while" loops.
     
        (1994-11-29)