countermand[verb]Synonyms: cancel, annul, override, repeal, rescind, retract, reverse, revoke 
 [TahlilGaran] English Synonym Dictionary ▲
 coun‧ter‧mand /ˌkaʊntəˈmɑːnd, ˈkaʊntəmɑːnd $ ˌkaʊntərˈmænd/ 
 verb [transitive] formal[
Date: 1400-1500; 
Language: French; 
Origin: contremander, from contre- ( ⇒ counter-) + mander 'to command' (from Latin mandare)]
 to officially tell people to ignore an order, especially by giving them a different one: 
 Terrorists tried to force him to countermand the order to attack.
 Terrorists tried to force him to countermand the order to attack.  [TahlilGaran] Dictionary of Contemporary English ▲