The Collaborative International Dictionary of English v.0.48:

Regrate \Re*grate"\ (r?*gr?t"), v. t. [imp. & p. p. Regrated;
   p. pr. & vb. n. Regrating.] [F. regratter, literally, to
   scrape again. See Re-, and Grate, v. t.]
   1. (Masonry) To remove the outer surface of, as of an old
      hewn stone, so as to give it a fresh appearance.
      [1913 Webster]

   2. To offend; to shock. [Obs.] --Derham.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

REGRATING, crim. law. Every practice or device, by act, conspiracy, words,
or news, to enhance the price of victuals or other merchandise, is so
denominated. 3 Inst. 196; 1 Russ. on Cr. 169.
     2. In the Roman law, persons who monopolized grain, and other produce
of the earth, were called dardanarii, and were variously punished. Dig. 47,
11, 6.