The Collaborative International Dictionary of English v.0.48:

Crenature \Cren"a*ture\ (kr?n"?-t?r or kr?"n?-; 135), n.
   1. (Bot.) A rounded tooth or notch of a crenate leaf, or any
      part that is crenate; -- called also crenelle.
      [1913 Webster]

   2. The state of being crenated or notched.
      [1913 Webster]

WordNet (r) 3.0 (2006):

crenature
    n 1: one of a series of rounded projections (or the notches
         between them) formed by curves along an edge (as the edge
         of a leaf or piece of cloth or the margin of a shell or a
         shriveled red blood cell observed in a hypertonic solution
         etc.) [syn: scallop, crenation, crenature, crenel,
         crenelle]