harmonica
Pronunciation: /hɑːˈmɒnɪkə/
noun
- a small rectangular wind instrument with a row of metal reeds along its length, held against the lips and moved from side to side to produce different notes by blowing or sucking. Also called mouth organ.

Origin:
mid 18th century: from Latin, feminine singular or neuter plural of harmonicus 'musical' (see harmonic)