1590s, from horse (n.) + chestnut. A tree probably native to Asia, introduced in England c. 1550; the name also was extended to similar North American species such as the buckeye. Said to have been so called because it was food for horses, "but this is appar. a mere guess" [Century Dictionary] and the sense is perhaps "large," as in horseradish. The nut resembles that of the edible chestnut but is bitter to the taste.
Entries linking to horse-chestnut
"solidungulate perissodactyl mammal of the family Equidæ and genus Equus" [Century Dictionary], Old English hors "horse," from Proto-Germanic *harss- (source also of Old Norse hross, Old Frisian, Old Saxon hors, Middle Dutch ors, Dutch ros, Old High German hros, German Roß "horse"), of unknown origin. By some, connected to PIE root *kers- "to run," source of Latin currere "to run." Boutkan prefers the theory that it is a loan-word from an Iranian language (Sarmatian) also borrowed into Uralic (compare Finnish varsa "foal"),
The usual Indo-European word is represented by Old English eoh, Greek hippos, Latin equus, from PIE root *ekwo-. Another Germanic "horse" word is Old English vicg, from Proto-Germanic *wegja- (source also of Old Frisian wegk-, Old Saxon wigg, Old Norse vigg), which is of uncertain origin. In many other languages, as in English, this root has been lost in favor of synonyms, probably via superstitious taboo on uttering the name of an animal so important in Indo-European religion. For the Romanic words (French cheval, Spanish caballo) see cavalier (n.); for Dutch paard, German Pferd, see palfrey; for Swedish häst, Danish hest see henchman. As plural Old English had collective singular horse as well as horses, in Middle English also sometimes horsen, but horses has been the usual plural since 17c.
Used at least since late 14c. of various devices or appliances which suggest a horse (as in sawhorse), typically in reference to being "that upon which something is mounted." For sense of "large, coarse," see horseradish. Slang use for "heroin" is attested by 1950. To ride a horse that was foaled of an acorn (1670s) was through early 19c. a way to say "be hanged from the gallows." Horse latitudes first attested 1777, the name of unknown origin, despite much speculation. Horse-pistol, "large one-handed pistol used by horseback riders," is by 1704. A dead horse as a figure for something that has ceased to be useful is from 1630s; to flog a dead horse "attempt to revive interest in a worn-out topic" is from 1864.
HORSEGODMOTHER, a large masculine wench; one whom it is difficult to rank among the purest and gentlest portion of the community. [John Trotter Brockett, "A Glossary of North Country Words," 1829]
The term itself is attested from 1560s. The horse's mouth as a source of reliable information is from 1921, perhaps originally of racetrack tips, from the fact that a horse's age can be determined accurately by looking at its teeth. To swap horses while crossing the river (a bad idea) is from the American Civil War and appears to have been originally one of Abe Lincoln's stories. Horse-and-buggy meaning "old-fashioned" is recorded from 1926 slang, originally in reference to a "young lady out of date, with long hair." To hold (one's) horses "restrain one's enthusiasm, be patient" is from 1842, American English; the notion is of keeping a tight grip on the reins.
type of tall tree native to western Asia, southern Europe, and eastern U.S., also the large "nut" that it produces, 1560s, from chesten nut (1510s), with superfluous nut (n.) + Middle English chasteine, from Old French chastain (12c., Modern French châtaigne), from Latin castanea "chestnut, chestnut tree," from Greek kastaneia, which the Greeks explained as either "nut from Castanea" in Pontus, or "nut from Castana" in Thessaly, but probably both places are named for the trees, not the other way around, and the word is borrowed from a language of Asia Minor (compare Armenian kask "chestnut," kaskeni "chestnut tree"). In reference to the dark reddish-brown color, 1650s. Applied to the horse-chestnut by 1832.
Slang sense of "venerable joke or story" is from 1885, explained by U.S. actor Joseph Jefferson ("Lippincott's Monthly Magazine," January 1888) as probably abstracted from the 1816 melodrama "The Broken Sword" by William Dimond where an oft-repeated story involving a chestnut tree figures in an exchange between the characters "Captain Zavior" and "Pablo":
Zav. Let me see—aye! it is exactly six years since, that peace being restored to Spain, and my ship paid off, my kind brother offer'd me a snug hammock in the dwelling of my forefathers;—I mounted a mule at Barcelona, and trotted away for my native mountains. At the dawn of the fourth day's journey, I entered the wood of Collares, when, suddenly from the thick boughs of a cork-tree—
Pab. [Jumping up.] A chesnut, Captain, a chesnut!
Zav. Bah! you booby, I say, a cork.
Pab. And I swear, a chesnut—Captain! this is the twenty-seventh time I have heard you relate this story, and you invariably said, a chesnut, till now.
Zav. Did I? Well, a chesnut be it then. But, take your seat again.
Jefferson traced the connection through William Warren (1812-1888), "the veteran comedian of Boston" (and Jefferson's cousin) who often played Pablo in the melodrama.
also horse-radish, 1590s, Cochlearia armoricia; the common name preserves the once-common figurative adjectival sense of horse as "strong, large, coarse," as in in obsolete horse mushroom (1866), horse-balm (1808), horse parsley, horse-mussel, Old English horsminte "horse mint." The "London Encyclopaedia" (1829) has horse emmet for a large kind of ant and horse marten "a kind of large bee." Also see radish.
Some nations have used the word bull as an augmentative; the English use the word horse, this being no doubt the largest animal of their acquaintance before the southern breeds of oxen were introduced.
[The Annual Review, London, 1804]