1610s, "sum, amount," from Latin quantum (plural quanta) "as much as, so much as; how much? how far? how great an extent?" neuter singular of correlative pronominal adjective quantus "as much" (see quantity).
The word was introduced in physics directly from Latin by Max Planck, 1900, on the notion of "minimum amount of a quantity which can exist;" reinforced by Einstein, 1905. Quantum theory is from 1912; quantum mechanics, 1922. The term quantum jump "abrupt transition from one stationary state to another" is recorded by 1954; quantum leap "sudden large advance" (1963), is often figurative.
"black man," 1838, American English, originally the name of a black minstrel character in a popular song-and-dance act by T.D. Rice (1808-1860) that debuted 1828 and attained national popularity by 1832:
Wheel about, an' turn about, an' do jis so;
Eb'ry time I wheel about, I jump Jim Crow.
Where and how Rice got it, or wrote it, is a mystery. Even before that, crow (n.) had been a derogatory term for a black man. As an adjective from 1833, in reference to the song. Association with segregation dates from 1841, in reference to separate railroad cars for blacks in Massachusetts. Modern use as a type of racial discrimination is from 1943. Jim Crow also could be a reference to someone's change of (political) principles (1837, from the "jump" in the song) or reversible machinery (1875, "wheel about").
On his arrival in Boston, Mr. [Charles Lenox] R[emond] went to the Eastern rail-road depot, in order to visit his parents in Salem; but, instead of being allowed to ride with other passengers, he was compelled to take a seat in what is contemptuously called the "Jim Crow car," as though he were a leper or a wild animal! [Annual Report of the Massachusetts Anti-Slavery Society, 1842]
The meaning "racy, sexy" is from 1866, from salt in the sense of "that which gives life or pungency" (1570s, originally in reference to words or wit); salt (adj.) also was used of lecherous (female) dogs, etc. (1540s) and also of persons (16c.-17c.).
The U.S. slang sense of "angry, irritated" is first attested 1938 (perhaps from similar use with regard to sailors, "tough, aggressive," which is attested by 1920), especially in phrase jump salty "unexpectedly become enraged" (1938). Related: Saltily.
Meaning "omit intervening parts" first recorded late 14c. Meaning "fail to attend" is from 1905. Meaning "to cause to skip or bound" is from 1680s. The custom of skipping rope has been traced to 17c.; it was commonly done by boys as well as girls until late 19c.
[Young's book] imagined an elite that got its position not from ancestry, but from test scores and effort. For him, meritocracy was a negative term; his spoof was a warning about the negative consequences of assigning social status based on formal educational qualifications, and showed how excluding from leadership anyone who couldn't jump through the educational hoops would create a new form of discrimination. And that's exactly what has happened. [Lani Guinier, interview, New York Times, Feb. 7, 2015]
Used as temporary fencing in agriculture. Sense of "barrier to jump in a race" is by 1822 (hurdle-race also is from 1822); hurdles as a type of race (originally horse race) with hurdles as obstacles is attested by 1836. Figurative sense of "obstacle" is 1924.
To be figuratively on the fence "uncommitted" is from 1828, perhaps from the notion of spectators at a fight, or a simple literal image: "A man sitting on the top of a fence, can jump down on either side with equal facility." [Bartlett, "Dictionary of Americanisms," 1848].
late 12c., scornen, "act contemptuously;" early 13c., "feel scorn or contempt, be contemptuous;" late 13c., transitive, "hold in scorn or contempt;" from Anglo-French, Old North French escarnir (Old French escharnir), a common Romanic verb (Spanish escarnir, Italian schernire), from a Germanic source, from Proto-Germanic *skarnjan "mock, deride" (source also of Middle High German scherzen "to jump with joy, Old High German skernon, Middle Dutch schernen). Related: Scorned; scorning.
OED rejects the suggestion that the vowel change in the Romanic languages might be by influence of or confusion with Old French escorner "deprive of horns," hence "deprive of honor or ornament, disgrace," from Vulgar Latin *excornare (source of Italian scornare "treat with contempt"), from Latin ex- "without" (see ex-) + cornu "horn" (see horn (n.)).
"an animal resembling a serpent, with legs added to it" [Johnson], late 14c., lusarde, from Anglo-French lusard, Old French laisarde "lizard" (Modern French lézard), from Latin lacertus (fem. lacerta) "lizard," a word of unknown origin. The ending in French and English is probably influenced by words in -ard.
It is identical to Latin lacertum "upper arm, muscular part of the arm, from the shoulder to the elbow" (opposed to bracchium), which suggests a pattern similar to that of Latin musculus "a muscle," literally "little mouse" (diminutive of mus "mouse"), so called because the shape and movement of the biceps were thought to resemble mice. It is unclear which Latin sense, the arm-muscle or the lizard, is original. De Vaan finds the words perhaps connected to Greek likertizein "to jump, dance," which Beekes finds likely from Pre-Greek.
Run fast, stand still. This, the lesson from lizards. [Ray Bradbury]
"separated by force into parts, not integral or entire," past-participle adjective from Old English brocken, past participle of break (v.). Of terrain, "rough," 1590s; of language, "imperfect, ungrammatical," 1590s. Related: Brokenly; brokenness. Broken home, one in which the parents of children no longer live together, is from 1846. Broken record in reference to someone continually repeating the same thing is from 1944, in reference to scratches on phonograph disks that cause the needle to jump back and repeat.
When Britain's Minister of State, Selwyn Lloyd[,] became bored with a speech by Russia's Andrei Vishinsky in UN debate, he borrowed a Dizzy Gillespie bebop expression and commented: "Dig that broken record." While most translators pondered the meaning, a man who takes English and puts it into Chinese gave this translation: "Recover the phonograph record which you have discarded." [Jet, Oct. 15, 1953]