Source : Webster's Revised Unabridged Dictionary (1913)

Countermand \Coun`ter*mand"\ (koun`t[~e]r*m[.a]nd"), v. t. [imp.
   & p. p. {Countermanded}; p. pr. & vb. n. {Countermanding}.]
   [F. contremander; contre (L. contra) + mander to command, fr.
   L. mandare. Cf. {Mandate}.]
   1. To revoke (a former command); to cancel or rescind by
      giving an order contrary to one previously given; as, to
      countermand an order for goods.

   2. To prohibit; to forbid. [Obs.]

            Avicen countermands letting blood in choleric
            bodles.                               --Harvey.

   3. To oppose; to revoke the command of.

            For us to alter anything, is to lift ourselves
            against God; and, as it were, to countermand him.
                                                  --Hooker.

Countermand \Coun"ter*mand\ (koun"t[~e]r*m[.a]nd), n.
   A contrary order; revocation of a former order or command.

         Have you no countermand for Claudio yet, But he must
         die to-morrow?                           --Shak.

Source : WordNet®

countermand
     n : a contrary command cancelling or reversing a previous
         command
     v : annul by recalling or rescinding; "He revoked the ban on
         smoking"; "lift an embargo"; "vacate a death sentence"
         [syn: {revoke}, {annul}, {lift}, {reverse}, {repeal}, {overturn},
          {rescind}, {vacate}]