a messenger, a person sent on a mission for someone else
a person charged with a delicate, or even secret, mission
adjective, Latin e = out, and emissum = sent out; emissary vein, one connecting intra- with extra-cranial venous channels.
(Apostle)--Meaning “special messenger,†“envoy†or “ambassador†(Hebrew malak; Greek apostolos; Latin apostolus).