Countermand (v. t.): 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.
Countermand (v. t.): To prohibit; to forbid.
Countermand (v. t.): To oppose; to revoke the command of.
Countermand (n.): A contrary order; revocation of a former order or command.
Countermand (n): A contrary command cancelling or reversing a previous command
Countermand (v): Cancel officially