(n) any agent (person or animal or microorganism) that carries and transmits a disease, Syn. transmitter, Example:mosquitos are vectors of malaria and yellow fever; fleas are vectors of the plague; aphids are transmitters of plant diseases; when medical scientists talk about vectors they are usually talking about insects
The Collaborative International Dictionary of English (GCIDE) v.0.53 Collaborative International Dictionary (GCIDE)
n. One who, or that which, transmits; specifically, that portion of a telegraphic or telephonic instrument by means of which a message is sent; -- opposed to receiver. [ 1913 Webster ]