The Collaborative International Dictionary of English v.0.48:

Engrail \En*grail"\, v. t. [imp. & p. p. Engrailed; p. pr. &
   vb. n. Engrailing.] [F. engr[^e]ler; pref. en- (L. in) +
   gr[^e]le hail. See Grail gravel.]
   1. To variegate or spot, as with hail.
      [1913 Webster]

            A caldron new engrailed with twenty hues. --Chapman.
      [1913 Webster]

   2. (Her.) To indent with small curves. See Engrailed.
      [1913 Webster]