transmitter (n.)

"send over, onward, or along," c. 1400, from Latin transmittere "send across, cause to go across, transfer, pass on," from trans "across, beyond" (see trans-) + mittere "to release, let go; send, throw" (see mission). Related: Transmitted; transmitting.

"chemical substance which transmits an impulse from one nerve fiber to another or others," 1959, from neuro- + transmitter.

1934, from a merger of transmitter + receiver.