Or·gan n.
 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.
 Note: ☞ 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.  A newsletter distributed within an organization is often called its house organ.
 5.  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.
 Note: ☞ Chaucer used the form orgon as a plural.
    The merry orgon . . . that in the church goon [go].
 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 Zool., a Tasmanian crow shrike (Gymnorhina organicum).  It utters discordant notes like those of a hand organ out of tune.
 Organ fish Zool., 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. Zool. See Tubipora.
 Organ point Mus., a passage in which the tonic or dominant is sustained continuously by one part, while the other parts move.
 Great a. [Compar. Greater superl. Greatest.]
 1. Large in space; of much size; big; immense; enormous; expanded; -- opposed to small and little; as, a great house, ship, farm, plain, distance, length.
 2. Large in number; numerous; as, a great company, multitude, series, etc.
 3. Long continued; lengthened in duration; prolonged in time; as, a great while; a great interval.
 4. Superior; admirable; commanding; -- applied to thoughts, actions, and feelings.
 5. Endowed with extraordinary powers; uncommonly gifted; able to accomplish vast results; strong; powerful; mighty; noble; as, a great hero, scholar, genius, philosopher, etc.
 6. Holding a chief position; elevated: lofty: eminent; distinguished; foremost; principal; as, great men; the great seal; the great marshal, etc.
    He doth object I am too great of birth.   --Shak.
 7. Entitled to earnest consideration; weighty; important; as, a great argument, truth, or principle.
 8. Pregnant; big (with young).
    The ewes great with young.   --Ps. lxxviii. 71.
 9. More than ordinary in degree; very considerable in degree; as, to use great caution; to be in great pain.
 We have all
 Great cause to give great thanks.   --Shak.
 10. Genealogy Older, younger, or more remote, by single generation; -- often used before grand to indicate one degree more remote in the direct line of descent; as, great-grandfather (a grandfather's or a grandmother's father), great-grandson, etc.
 Great bear (Astron.), the constellation Ursa Major.
 Great cattle (Law), all manner of cattle except sheep and yearlings. --Wharton.
 Great charter Eng. Hist., Magna Charta.
 Great circle of a sphere, a circle the plane of which passes through the center of the sphere.
 Great circle sailing, the process or art of conducting a ship on a great circle of the globe or on the shortest arc between two places.
 Great go, the final examination for a degree at the University of Oxford, England; -- called also greats.  --T. Hughes.
 Great guns. Naut. See under Gun.
 The Great Lakes the large fresh-water lakes (Lakes Superior, Michigan, Huron, Erie, and Ontario) which lie on the northern borders of the United States.
 Great master.  Same as Grand master, under Grand.
 Great organ  Mus., the largest and loudest of the three parts of a grand organ (the others being the choir organ and the swell, and sometimes the pedal organ or foot keys), It is played upon by a separate keyboard, which has the middle position.
 The great powers (of Europe), in modern diplomacy, Great Britain, France, Germany, Austria, Russia, and Italy.
 Great primer. See under Type.
 Great scale (Mus.), the complete scale; -- employed to designate the entire series of musical sounds from lowest to highest.
 Great sea, the Mediterranean sea. In Chaucer both the Black and the Mediterranean seas are so called.
 Great seal. (a) The principal seal of a kingdom or state. (b) In Great Britain, the lord chancellor  (who is custodian of this seal); also, his office.
 Great tithes. See under Tithes.
 The great, the eminent, distinguished, or powerful.
 The Great Spirit, among the North American Indians, their chief or principal deity.
 To be great (with one), to be intimate or familiar (with him). --Bacon.