society > communication > telecommunication > telegraphy or telephony > telegraphy > telegraph > [noun] > transmitter > key (3)
a small hand-operated lever or other device in a telegraphic transmitter, used to alternately make and break the circuit; cf. key, n.1 20.
a key forming part of the Morse telegraph apparatus, which is pressed and released to send signals in Morse code.
That which taps or lightly strikes, as a hammer for striking a bell; spec. a key in an electric telegraph which is depressed (with a tapping…