one-horse adj.

"being but a single unit or individual; being a single person, thing, etc. of the mentioned;" as a pronoun, "a single person or thing, an individual, somebody;" as a noun, "the first or lowest of the cardinal numerals; single in kind, the same; the first whole number, consisting of a single unit; unity; the symbol representing one or unity;" c. 1200, from Old English an (adjective, pronoun, noun) "one," from Proto-Germanic *ainaz (source also of Old Norse einn, Danish een, Old Frisian an, Dutch een, German ein, Gothic ains), from PIE root *oi-no- "one, unique."

Originally pronounced as it still is in only, atone, alone, and in dialectal good 'un, young 'un, etc.; the now-standard pronunciation "wun" began c. 14c. in southwest and west England (Tyndale, a Gloucester man, spells it won in his Bible translation), and it began to be general 18c. Its use as indefinite pronoun was influenced by unrelated French on and Latin homo.

Before the name of a person, indicating "hitherto unknown" or not known to the speaker.

One and only "sweetheart" is from 1906. Slang one-arm bandit for a type of slot machine is recorded by 1938. One-night stand is 1880 in performance sense; 1963 in sexual sense. One of the boys "ordinary amiable fellow" is from 1893. One-track mind "mind capable of only one line of thought or action" is by 1915. Drinking expression one for the road is from 1950 (as a song title). One-man band is by 1909 in a literal sense, 1914 figurative. One of those things "unpredictable occurrence" is from 1934 (Cole Porter's song is from 1935).

The conscience clause is one of the weaknesses of the Bill. It is one of those things which tend to create the bitterness. The conscience clause is one of those things which are inseparable from a Bill like this. It is one of those things which divides the sheep from the goats—members can pick them out for themselves—in the playground, in the school. ["Religious Exercises in School Bills," New Zealand Parliamentary Debates, Aug. 13, 1926]

"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.