The Collaborative International Dictionary of English v.0.48:

Crenelate \Cren"el*ate\ (kr?n"?l-?t or kr?"n?l-?t), v. t. [imp.
   & p. p. Crenelated (-?`t?d); p. pr. & vb. n. Crenelating
   (-?`t?ng).] [LL. crenellare, kernellare: cf. F. cr?neler to
   indent. See Crenelle.] [Written also crenellate.]
   1. To furnish with crenelles.
      [1913 Webster]

   2. To indent; to notch; as, a crenelated leaf.
      [1913 Webster]

   Crenelated molding (Arch.), a kind of indented molding used
      in Norman buildings.
      [1913 Webster]

WordNet (r) 3.0 (2006):

crenellate
    v 1: supply with battlements [syn: crenel, crenelate,
         crenellate]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "crenellate":
   Vandyke, arm, armor, armor-plate, bank, barricade, battle, blaze,
   blockade, bulwark, castellate, chop, crenulate, crimp, cut, dig in,
   embattle, entrench, fence, fortify, garrison, gash, incise, indent,
   jag, knurl, machicolate, man, man the garrison, mill, mine, nick,
   notch, palisade, picot, pink, scallop, scarify, score, scotch,
   serrate, slash, tooth, wall