{ Ka*lei"do*phon (?), Ka*lei"do*phone (?), } [Gr. &?; beautiful + &?; appearance, form + &?; sound.] (Physics.) An instrument invented by Professor Wheatstone, consisting of a reflecting knob at the end of a vibrating rod or thin plate, for making visible, in the motion of a point of light reflected from the knob, the paths or curves corresponding with the musical notes produced by the vibrations.