Definition of harmonica in US English:



  • 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
    • ‘He first started entertaining the other deckhands with his harmonica and then added the guitar.’
    • ‘He blew into his harmonica with the microphone pressed hard up to its air outlets.’
    • ‘The music is a unique sound of Irish folk ballads, traditional tunes with vocals accompanied by bazouki, bodhrán, harmonicas and whistles.’
    • ‘He recalled his amazement at seeing his friend play the harmonica with one hand while accompanying himself on the piano.’
    • ‘Finally he turned around, a harmonica pressed up against his mouth as he blew in and out.’


Mid 18th century: from Latin, feminine singular or neuter plural of harmonicus ‘musical’ (see harmonic).