- a diplomatic official of the highest rank, sent by one sovereign or state to another as its resident representative (ambassador extraordinary and plenipotentiary ).
- a diplomatic official of the highest rank sent by a government to represent it on a temporary mission, as for negotiating a treaty.
- a diplomatic official serving as permanent head of a country's mission to the United Nations or some other international organization.
- an authorized messenger or representative. Abbreviation: Amb., amb.
- short for ambassador extraordinary and plenipotentiary; a diplomatic minister of the highest rank, accredited as permanent representative to another country or sovereign
- a diplomatic minister of the highest rank sent on a special mission
- a diplomatic minister of the first rank with treaty-signing powers
- an ambassador with special duties who may be sent to more than one government
- an authorized representative or messenger
