'armonica' originates from Italian, specifically the word 'armonica', ultimately from Latin 'harmonicus' and Greek 'harmōnikós', where Greek 'harmōnía' meant 'agreement, joining (of parts)'.

'armonica' changed from Greek 'harmōnikós' to Latin 'harmonicus' and through Late Latin/Old Italian forms became the modern Italian/Spanish word 'armonica'.

Initially it meant 'pertaining to harmony' (adjective); over time the form was also used as a noun to name the instrument (the harmonica), so the meaning broadened from a descriptive sense to include the musical instrument.