Source : Webster's Revised Unabridged Dictionary (1913)

Sticker \Stick"er\, n.
   1. One who, or that which, sticks; as, a bill sticker.

   2. That which causes one to stick; that which puzzles or
      poses. [Colloq.] --Tackeray.

   3. (Mus.) In the organ, a small wooden rod which connects (in
      part) a key and a pallet, so as to communicate motion by
      pushing.

   4. Same as {Paster}, 2. [Political Cant, U.S.]

Source : WordNet®

sticker
     n 1: a sharp-pointed tip on a stem or leaf [syn: {spine}, {thorn},
           {prickle}, {pricker}]
     2: an adhesive label [syn: {gummed label}, {paster}]
     3: a particularly difficult or baffling question or problem
        [syn: {poser}, {stumper}, {toughie}]
     4: a short knife with a pointed blade used for piercing or
        stabbing [syn: {dagger}]