The Collaborative International Dictionary of English v.0.48:

Pruning \Prun"ing\, n.
   1. The act of trimming, or removing what is superfluous.
      [1913 Webster]

   2. (Falconry) That which is cast off by bird in pruning her
      feathers; leavings. --Beau. & Fl.
      [1913 Webster]

   Pruning hook, or Pruning knife, cutting instrument used
      in pruning trees, etc.

   Pruning shears, shears for pruning trees, vines, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pruning knife
    n 1: a knife with a curved or hooked blade