[1] : The Collaborative International Dictionary of English v.0.48

knap \knap\, v. t. imp.  p. p. knapped; p. pr.  vb. n.
   knapping. d. knappen to chew, bite, crack, take hold of;
   prob. of imitative origin.
   1. to bite; to bite off; to break short. obs. or prov. eng.
      
      1913 webster

            he will knap the spears apieces with his teeth.
                                                  --dr. h. more.
      1913 webster

            he breaketh the bow, and knappeth the spear in
            sunder.                               --ps. xlvi. 9
                                                  book of
                                                  common
                                                  prayer.
      1913 webster

   2. to strike smartly; to rap; to snap. chiefly brit.
      --bacon.
      1913 webster
see also:
knapped knapping 

[2] : WordNet (r) 2.0

knap
     v 1: strike sharply; "rap him on the knuckles" syn: rap
     2: break a small piece off from; "chip the glass"; "chip a
        tooth" syn: chip, cut off, break off
     also: knapping, knapped
see also:
rap chip cut off break off knapping knapped 

[3] : WordNet (r) 2.0

knapped
     see knap
see also:
knap 

Knapped >> K Words
Knapped, definition of term: Knapped
knapped_pag1.html