GNU Collaborative International Dictionary of English

Found 2 definitions

1.       
   Harmonica , n. [Fem. fr. L. harmonicus harmonic. See Harmonic, n. ]
   A musical instrument, consisting of a series of hemispherical glasses which, by touching the edges with the dampened finger, give forth the tones; it is now called the glass harmonica, to distinguish it from the common harmonica, formerly called the harmonicon.
   1913 Webster
   A toy instrument of strips of glass or metal hung on two tapes, and struck with hammers.
   1913 Webster
   A small wind musical instrument shaped like a flat bar with holes along the thin edges, held in the hand and producing notes from multiple vibrating reeds arranged inside along its length; it was formerly called the harmonicon. See harmonicon.
   PJC
         
       

2.       
   Harmonicon , n. A small, flat, wind instrument of music, in which the notes are produced by the vibration of free metallic reeds; it is now called the harmonica.
   1913 Webster
   +PJC