A musical instrument similar in shape and action to a pianoforte, but having tuning-forks in place of strings.(noun)
The Century Dictionary (Public Domain)
Use "key-harp" in a sentence
"The key-harp on the corner of the table was something like a miniature piano, except the volume was so low that it was clearly useless except as a composing or learning aid."
"As the tinted glass of the bedchamber window filtered the worst of the late-afternoon sun, Anna sat at the table with the key-harp, a stack of the tan paper, a pencil, and the inevitable pitcher of water and accompanying goblet."
"Even though her left shoulder and hand had healed enough to use the key-harp for short periods of time, the instrument seemed almost worse than useless."