2. any agent (person or animal or microorganism) that carries and transmits a disease
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
3. set used to broadcast radio or tv signals
4. 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.