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.
Origin: 1325–75; ME am-, embass(i)adour, imbassadore < AF ambassateur, ambassaduer < It ambassatore, dial. It ambassadore, equiv. to ambass- (see embassy) -atore, -adore < L -ātōrem acc. of -ātor-ator
A diplomatic official of the highest rank appointed and accredited as representative in residence by one government or sovereign to another, usually for a specific length of time.
A diplomatic official heading his or her country's permanent mission to certain international organizations, such as the United Nations.
An authorized messenger or representative.
An unofficial representative: ambassadors of goodwill.
[Middle English ambassadour, from Old French ambassadeur, from Medieval Latin ambactia, mission, from Latin ambactus, servant, ultimately of Celtic origin; see ag- in Indo-European roots.] am·bas'sa·do'ri·al (-dôr'ē-əl, -dōr'-) adj., am·bas'sa·dor·ship' n.
[am-bas-uh-der, -dawr] 
