| 1. | a diplomatic official of the highest rank, sent by one sovereign or state to another as its resident representative (ambassador extraordinary and plenipotentiary). |
| 2. | a diplomatic official of the highest rank sent by a government to represent it on a temporary mission, as for negotiating a treaty. |
| 3. | a diplomatic official serving as permanent head of a country's mission to the United Nations or some other international organization. |
| 4. | an authorized messenger or representative. Abbreviation: Amb., amb. |