The Collaborative International Dictionary of English v.0.48:

pestle \pes"tle\, v. t. & i. [imp. & p. p. Pestled; p. pr. &
   vb. n. Pestling.]
   To pound, pulverize, bray, or mix with a pestle, or as with a
   pestle; to use a pestle.
   [1913 Webster]