Old English horn "horn of an animal; projection, pinnacle," also "wind instrument" (originally one made from animal horns), from Proto-Germanic *hurni- (source also of German Horn, Dutch horen, Old Frisian horn, Gothic haurn), from PIE root *ker- (1) "horn; head."

Late 14c. as "one of the tips of the crescent moon." The name was retained for a class of musical instruments that developed from the hunting horn; the French horn is the true representative of the class. Of dilemmas from 1540s; of automobile warning signals from 1901. Slang meaning "erect penis" is suggested by c. 1600. Jazz slang sense of "trumpet" is by 1921. Meaning "telephone" is by 1945. Figurative senses of Latin cornu included "salient point, chief argument; wing, flank; power, courage, strength." Horn of plenty is from 1580s. To make horns at "hold up the fist with the two exterior fingers extended" as a gesture of insult is from c.1600.

Symbolic of cuckoldry since mid-15c. (the victim was fancied to grow one on his head). The image is widespread in Europe and perhaps as old as ancient Greece. The German linguist Hermann Dunger ('Hörner Aufsetzen' und 'Hahnrei', "Germania" 29, 1884) ascribes it to a custom surviving into 19c., "the old practice of engrafting the spurs of a castrated cock on the root of the excised comb, which caused them to grow like horns" [James Hastings, "Encyclopedia of Religion and Ethics"] but the image could have grown as well from a general gesture of contempt or insult made to wronged husbands, "who have been the subject of popular jest in all ages" [Hastings].

"abundant, plentiful," mid-14c., from Latin copiosus "plentiful," from copia "an abundance, ample supply, profusion, plenty; riches, prosperity; ability, power, might," also the name of the Roman goddess of abundance," from assimilated form of com "with, together" (see com-) + ops (genitive opis) "power, wealth, resources," from PIE root *op- "to work, produce in abundance." Related: Copiously; copiousness.

Proto-Indo-European root meaning "horn; head," with derivatives referring to horned animals, horn-shaped objects, and projecting parts.

It forms all or part of: alpenhorn; Capricorn; carat; carotid; carrot; carotene; cerato-; cerebellum; cerebral; cerebrum; cervical; cervix; charivari; cheer; chelicerae; corn (n.2) "hardening of the skin;" cornea; corner; cornet; cornucopia; cranium; flugelhorn; hart; hartebeest; horn; hornbeam; hornblende; hornet; keratin; kerato-; migraine; monoceros; reindeer; rhinoceros; saveloy; serval; triceratops; unicorn.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit srngam "horn;" Persian sar "head," Avestan sarah- "head;" Greek karnon "horn," koryne "club, mace," koryphe "head;" Latin cornu "horn," cervus "deer;" Old English horn "horn of an animal;" Welsh carw "deer."

Proto-Indo-European root meaning "to work, produce in abundance."

It forms all or part of: cooperate; cooperation; copious; copy; cornucopia; hors d'oeuvre; inure; maneuver; manure; oeuvre; office; official; officinal; omni-; omnibus; omnium gatherum; op. cit.; opera; operate; operation; operose; optimism; optimum; opulence; opulent; opus; Oscan.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit apas- "work, religious act," apnas- "possession, property;" Hittite happina- "rich;" Avestan huapah- "doing good work, masterly;" Latin opus "a work, labor, exertion;" Greek ompne "food, corn;" Old High German uoben "to start work, to practice, to honor;" German üben "to exercise, practice;" Dutch oefenen, Old Norse æfa, Danish øve "to exercise, practice;" Old English æfnan "to perform, work, do," afol "power."