Source : Webster's Revised Unabridged Dictionary (1913)

Countercheck \Coun`ter*check"\ (koun`t?r-ch?k"), v. t. [imp. &
   p. p. {Counterchecked} (-ch?ckt"); p. pr. & vb. n.
   {Counterchecking}.]
   To oppose or check by some obstacle; to check by a return
   check.

Countercheck \Coun"ter*check`\ (koun"t?r-ch?k`), n.
   1. A check; a stop; a rebuke, or censure to check a reprover.

   2. Any force or device designed to restrain another
      restraining force; a check upon a check.

            The system of checks and counterchecks. --J. H.
                                                  Newton.

Source : WordNet®

countercheck
     n 1: a check that restrains another check
     2: something that checks the correctness of a previous check
        [syn: {double check}]
     v 1: oppose or check by a counteraction [syn: {counteract}]
     2: check a second time