Harmonica (noun)

1. A small rectangular wind instrument that consists of a series of metal reeds, each of which produces a different pitch when air is blown into or drawn out of the instrument.
2. A small instrument that has a series of metal plates that you blow into or suck on to make different notes.

Origin:

German, from harmonisch harmonious, from latin harmonicus, from greek harmonikos, from harmonia.

Examples:

1. He could play a mean harmonica.
2. Harmonica is a popular instrument in blues, country and folk music.
3. He took out his harmonica and played a few notes.
4. The harmonica is a small, versatile instrument that can be played in many different styles.
5. The harmonica is also known as a mouth organ or a French harp.