harmonica(n = noun.artifact) harp, mouth harp, mouth organ - a small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole;
is a kind of free-reed instrument

1.  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]

2.  A toy instrument of strips of glass or metal hung on two tapes, and struck with hammers. [1913 Webster]

3.  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]

harmonica, n. 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.

Etymology:
L, fem. sing. or neut. pl. of harmonicus: see HARMONIC

N  musical instruments, band, string-band, brass-band, orchestra, orchestrina, monochord, polychord, harp, lyre, lute, archlute, mandola, mandolin, mandoline, guitar, zither, cither, cithern, gittern, rebeck, bandurria, bandura, banjo, bina, vina, xanorphica, viol, violin, fiddle, kit, viola, viola d'amore, viola di gamba, tenor, cremona, violoncello, bass, bass viol, base viol, theorbo, double base, contrabasso, violone, psaltery, bow, fiddlestick, piano, pianoforte, harpsichord, clavichord, clarichord, manichord, clavier, spinet, virginals, dulcimer, hurdy-gurdy, vielle, pianino, Eolian harp, organ, harmonium, harmoniphon, American organ, barrel organ, hand organ, accordion, seraphina, concertina, humming top, flute, fife, piccolo, flageolet, clarinet, claronet, basset horn, corno di bassetto, oboe, hautboy, cor Anglais, corno Inglese, bassoon, double bassoon, contrafagotto, serpent, bass clarinet, bagpipes, union pipes, musette, ocarina, Pandean pipes, reed instrument, sirene, pipe, pitch-pipe, sourdet, whistle, catcall, doodlesack, harmoniphone, horn, bugle, cornet, cornet-a-pistons, cornopean, clarion, trumpet, trombone, ophicleide, French horn, saxophone, sax, buglehorn, saxhorn, flugelhorn, althorn, helicanhorn, posthorn, sackbut, euphonium, bombardon tuba, cymbal, bell, gong, tambour, tambourine, tamborine, drum, tom-tom, tabor, tabret, tabourine, taborin, side drum, kettle drum, timpani, tympani, tymbal, timbrel, castanet, bones, musical glasses, musical stones, harmonica, sounding-board, rattle, tam-tam, zambomba, reed, tuning fork, triangle, Jew's harp, musical box, harmonicon, xylophone, sordine, sordet, sourdine, sourdet, mute, (iv) PERCEPTION OF SOUND.