Or″gan (?), n. [L. organum, Gr. �; akin to � work, and E. work: cf. F. organe. See Work, and cf. Orgue, Orgy.]
1. An instrument or medium by which some important action is performed, or an important end accomplished; as, legislatures, courts, armies, taxgatherers, etc., are organs of government.
2. (Biol.) A natural part or structure in an animal or a plant, capable of performing some special action (termed its function), which is essential to the life or well-being of the whole; as, the heart, lungs, etc., are organs of animals; the root, stem, foliage, etc., are organs of plants.
☞ In animals the organs are generally made up of several tissues, one of which usually predominates, and determines the principal function of the organ. Groups of organs constitute a system. See System.
3. A component part performing an essential office in the working of any complex machine; as, the cylinder, valves, crank, etc., are organs of the steam engine.
4. A medium of communication between one person or body and another; as, the secretary of state is the organ of communication between the government and a foreign power; a newspaper is the organ of its editor, or of a party, sect, etc.
5. [Cf. AS. organ, fr. L. organum.] (Mus.) A wind instrument containing numerous pipes of various dimensions and kinds, which are filled with wind from a bellows, and played upon by means of keys similar to those of a piano, and sometimes by foot keys or pedals; — formerly used in the plural, each pipe being considered an organ.
The deep, majestic, solemn organs blow. Pope.
☞ Chaucer used the form orgon as a plural.
The merry orgon... that in the church goon.
Barrel organ, Choir organ, Great organ, etc. See under Barrel, Choir, etc. — Cabinet organ(Mus.), an organ of small size, as for a chapel or for domestic use; a reed organ. — Organ bird(Zoöl.), a Tasmanian crow shrike (Gymnorhina organicum). It utters discordant notes like those of a hand organ out of tune. — Organ fish(Zoöl.), the drumfish. — Organ gun. (Mil.) Same as Orgue (b). — Organ harmonium(Mus.), an harmonium of large capacity and power. — Organ of Corti(Anat.), a complicated structure in the cochlea of the ear, including the auditory hair cells, the rods or fibers of Corti, the membrane of Corti, etc. See Note under Ear. — Organ pipe. See Pipe, n., 1. — Organ-pipe coral. (Zoöl.) See Tubipora. — Organ point(Mus.), a passage in which the tonic or dominant is sustained continuously by one part, while the other parts move.