1. A musical wind instrument consisting of a small rectangular case containing a set of metal reeds connected to a row of holes, over which the player places his/her mouth and exhales and inhales to produce the tones. Also known as a "mouth organ".
2. Any of various percussion instruments that use graduated bars of metal or other hard material as sound producers.
3. An instrument consisting of tuned strips of metal or glass fixed to a frame and struck with a hammer.

The term armonica was coined in 1762 by the American physicist and statesman, Benjamin Franklin, for a musical instrument consisting of a set of water-filled glasses tuned to different notes and played with the fingers.

Harmonica was first applied to the "mouth-organ" in 1873; which is an alteration of the earlier armonica or glass harmonica.