Definition of telegraph key in English:

telegraph key

noun

  • A button that is pressed to produce a signal when transmitting Morse code.

    • ‘With a clattering of telegraph keys, reporters sent news of the race to a world suddenly transfixed by the drama in the far north.’
    • ‘This was a five-key device based loosely on the telegraph key in which the transmission of information involved specific combinations of keys rather than the distinct meaning assigned to each key of the QWERTY typewriter keyboard.’
    • ‘Above each cylinder rests a fine platinum needle, or stylus, not unlike the point in a telegraph key.’