Online Etymology Dictionary

ruination (n.): 1660s, from verb ruinate "to go to ruin" (1540s), from Medieval Latin ruinatus, past participle of ruinare, from Latin ruina (see ruin (n.)).
ruinous (adj.): late 14c., "going to ruin," from Old French ruinos (Modern French ruineux) or directly from Latin ruinosus "tumbling down, going to ruin," from ruina (see ruin (n.)). Meaning "causing ruin" is from mid-15c. Related: Ruinously.
rule (n.): c. 1200, "principle or maxim governing conduct, formula to which conduct must be conformed" from Old French riule, Norman reule "rule, custom, (religious) order" (in Modern French partially re-Latinized as règle), from Vulgar Latin *regula, from Latin regula "straight stick, bar, ruler;" figuratively "a pattern, a model," related to regere "to rule, straighten, guide" (see regal). Replaced Old English wealdan.

Meaning "regulation governing play of a game, etc." is from 1690s. Phrase rule of thumb first attested 1690s. Rule of law "supremacy of impartial and well-defined laws to any individual's power" is from 1883. Meaning "strip used for making straight lines or measuring" is recorded from mid-14c. Typography sense is attested from 1680s.
rule (v.): c. 1200, "to control, guide, direct," from Old French riuler "impose rule," from Latin regulare (see regulate). Legal sense "establish by decision" is recorded from early 15c. Meaning "mark with lines" is from 1590s. Meaning "to dominate, prevail" is from 1874. "Rule Brittania," patriotic song, is from 1740. Related: Ruled; ruling.
ruler (n.): "one who rules," late 14c., agent noun from rule (v.). Meaning "instrument used for making straight lines" is c. 1400 (compare rule (n.)).
ruling (n.): "determination by a judge or court on a point arising in the course of a trial or hearing," 1550s, verbal noun from rule (v.).
ruly (adj.): "conforming to (religious) rule; amenable to rule, disciplined, orderly," reuleli; from rule (n.) + -ly (2).
rum (n.): "liquor from sugar cane or molasses," 1650s, shortening of rumbullion (1651), rombostion (1652), of uncertain origin, perhaps from rum (adj.).
The chiefe fudling they make in the Island [i.e. Barbados] is Rumbullion alias Kill-Devill, and this is made of suggar cane distilled, a hott, hellish and terrible liquor. ["A briefe Description of the Island of Barbados," 1651]
The English word was borrowed into Dutch, German, Swedish, Danish, Spanish, Portuguese, Italian, French, and Russian. Used since 1800 in North America as a general (hostile) name for intoxicating liquors.
Rum I take to be the name which unwashed moralists apply alike to the product distilled from molasses and the noblest juices of the vineyard. Burgundy in "all its sunset glow" is rum. Champagne, soul of "the foaming grape of Eastern France," is rum. ... Sir, I repudiate the loathsome vulgarism as an insult to the first miracle wrought by the Founder of our religion! [Oliver Wendell Holmes, "The Autocrat of the Breakfast-Table," 1891]
rum (adj.): "excellent, fine, good, valuable," 1560s, from rome "fine" (1560s), said to be from Romany rom "male, husband" (see Romany). E.g. rum kicks "Breeches of gold or silver brocade, or richly laced with gold or silver" [Grose, "Dictionary of the Vulgar Tongue," 1785].

A very common 16c. cant word, by 1774 it also had come to mean "odd, strange, bad, spurious," perhaps because it had been so often used approvingly by rogues in reference to one another. This was the main sense after c. 1800.
rum-runner (n.): "smuggler or transporter of illicit liquor," 1919, from rum (n.) + runner.
rumba (n.): 1919, from Cuban Spanish rumba, originally "spree, carousal," derived from Spanish rumbo "spree, party," earlier "ostentation, pomp, leadership," perhaps originally "the course of a ship," from rombo "rhombus," in reference to the compass, which is marked with a rhombus. The verb is recorded from 1932. Related: Rumbaed; rumbaing.
rumble (v.): late 14c., "make a deep, heavy, continuous sound," also "move with a rolling, thundering sound," also "create disorder and confusion," probably related to Middle Dutch rommelen "to rumble," Middle High German rummeln, Old Norse rymja "to shout, roar," all of imitative origin. Related: Rumbled; rumbling.
rumble (n.): late 14c., from rumble (v.). Slang noun meaning "gang fight" is from 1946. Meaning "backmost part of a carriage" is from 1808 (earlier rumbler, 1801), probably from the effect of sitting over the wheels; hence rumble seat (1828).
rumbustious (adj.): 1778, an arbitrary formation, part of what Farmer describes as "A class of colloquialisms compounded with an intensive prefix" (ram- or rum-), probably suggesting in part rum (adj.) in its old slang sense of "good, fine," and ramp (n.2). In this case apparently suggested by boisterous, robustious, bumptious, etc. Coined about the same time were rumbustical, rambumptious "conceited, self-assertive," ramgumptious "shrewd, bold, rash," rambuskious "rough," rumstrugenous. Also compare ramshackle, rambunctious.
rumen (n.): "first stomach of a ruminant," 1728, from Latin rumen "the throat," of uncertain origin.
ruminant (n.): 1660s, from Latin ruminantem (nominative ruminans), present participle of ruminare "to chew the cud" (see ruminate). As an adjective from 1670s.
ruminate (v.): 1530s, "to turn over in the mind," also "to chew cud" (1540s), from Latin ruminatus, past participle of ruminare "to chew the cud; turn over in the mind," from rumen (genitive ruminis) "gullet," of uncertain origin. Related: Ruminated; ruminating.
rumination (n.): c. 1600, "act of ruminating; act of meditating," from Latin ruminationem (nominative ruminatio) "a chewing the cud," noun of action from past participle stem of ruminare (see ruminate).
rummage (v.): 1540s, "arrange (cargo) in a ship," from rummage (n.), 1520s, "act of arranging cargo in a ship," a shortening of Middle French arrumage "arrangement of cargo," from arrumer "to stow goods in the hold of a ship," from a- "to" + rumer, probably from Germanic (compare Old Norse rum "compartment in a ship," Old High German rum "space," Old English rum; see room (n.)). Or else from English room (n.) + -age.

Meaning "to search closely (the hold of a ship), especially by moving things about" first recorded 1610s. Related: Rummaged; rummaging. Rummage sale (1803) originally was a sale at docks of unclaimed goods.
rummy (n.): card game, 1910, rhummy, of unknown origin. Gin rummy is first attested 1941. Meaning "drunkard" is 1851, from rum (n.). Meaning "opponent of temperance" in U.S. politics is from 1860.
rumor (n.): late 14c., from Old French rumor "commotion, widespread noise or report" (Modern French rumeur), from Latin rumorem (nominative rumor) "noise, clamor, common talk, hearsay, popular opinion," related to ravus "hoarse," from PIE *reu- "to bellow." Related: Rumorous. Rumor mill is from 1887. Dutch rumoer, German Rumor are from French.
rumor (v.): 1590s, "spread a rumor; spread by way of rumor," from rumor (n.). Related: Rumored; rumoring.
rumour: chiefly British English spelling of rumor; see -or. Related: Rumoured; rumouring.
rump (n.): "hind-quarters, buttocks of an animal," mid-15c., from a Scandinavian source (compare Danish, Norwegian rumpe, Swedish rumpa), from or corresponding to Middle Dutch romp, German Rumpf "trunk, torso." Sense of "small remnant" derives from "tail" and is first recorded 1640s in reference to the English Rump Parliament (December 1648-April 1653). As an adjective from c. 1600.
Rumpelstiltskin (n.): 1840, from German Rumpelstilzchen. The German form of the name is used in English from 1828.
rumple (v.): c. 1600, possibly a variant of rimple "to wrinkle" (c. 1400), from Old English hrympel "wrinkle" (possibly influenced by Middle Dutch rumpelen), related to Old English hrimpan "to fold, wrinkle" (see ramp (v.)). Related: Rumpled; rumpling. As a noun from c. 1500.
rumpus (n.): 1764, of unknown origin, "prob. a fanciful formation" [OED], possibly an alteration of robustious "boisterous, noisy" (1540s; see robust). First record of rumpus room "play room for children in a family home" is from 1938.
run (v.): the modern verb is a merger of two related Old English words, in both of which the first letters sometimes switched places. The first is intransitive rinnan, irnan "to run, flow, run together" (past tense ran, past participle runnen), cognate with Middle Dutch runnen, Old Saxon, Old High German, Gothic rinnan, German rinnen "to flow, run."

The second is Old English transitive weak verb ærnan, earnan "ride, run to, reach, gain by running" (probably a metathesis of *rennan), from Proto-Germanic *rannjanan, causative of the root *ren- "to run." This is cognate with Old Saxon renian, Old High German rennen, German rennen, Gothic rannjan.

Both are from PIE *ri-ne-a-, nasalized form of root *reie- "to flow, run" (see Rhine).

Of streams, etc., from c. 1200; of machinery, from 1560s. Meaning "be in charge of" is first attested 1861, originally American English. Meaning "seek office in an election" is from 1826, American English. Phrase run for it "take flight" is attested from 1640s. Many figurative uses are from horseracing or hunting (such as to run (something) into the ground, 1836, American English).

To run across "meet" is attested from 1855, American English. To run short "exhaust one's supply" is from 1752; to run out of in the same sense is from 1713. To run around with "consort with" is from 1887. Run away "flee in the face of danger" is from late 14c. To run late is from 1954.
run (n.): "a spell of running," mid-15c. (earlier ren, late 14c.), from run (v.). The Old English noun ryne meant "a flowing, a course, a watercourse." Modern sense of "small stream" first recorded 1580s, mostly Northern English dialect and American English.

Meaning "continuous stretch" (of something) is from 1670s. Meaning "series or rush of demands on a bank, etc." is first recorded 1690s. Meaning "the privilege of going through or over" is from 1755. Baseball sense is from 1856. Meaning "single trip by a railroad train" is from 1857. Military aircraft sense is from 1916. Meaning "total number of copies printed" is from 1909. Meaning "tear in a knitted garment" is from 1922. Phrase a run for one's money is from 1872 in a figurative sense, originally from horse racing, implying competition (1841).
run-down (adj.): 1866, of persons, with reference to health, from verbal phrase, from run (v.) + down (adv.). From 1896 of places; 1894 of clocks. Earliest sense is "oppressed" (1680s).
run-in (n.): "quarrel, confrontation," 1905, from verbal phrase, from run (v.) + in (adv.). From 1857 as "an act of running in."
run-of-the-mill (adj.): "unspectacular," 1909 in a literal sense, in reference to material yielded by a mill, etc., before sorting for quality (compare common run "usual, ordinary type," from 1712). Figurative use is from 1922.
run-through (n.): "a rehearsal," especially a hasty one, 1923, from the verbal phrase, from run (v.) + through (adv.).
run-up (n.): 1834, "an act of running upward," from verbal phrase, from run (v.) + up (adv.). Extended sense "period of time or sequence of events proceeding some important event" is from 1966.
runabout (n.): 1540s, in reference to persons, from run (v.) + about (adv.). From 1890 as a small, light type of carriage; later extended to motor cars.
runaround (n.): also run-around, "deceptive, evasive treatment," 1915, from verbal phrase, from run (v.) + around (adv.).
runaway (n.): 1540s, "one who flees," from verbal phrase, from run (v.) + away (adv.). Meaning "an act of running away" is from 1724.
runcible: 1871, a nonsense word coined by Edward Lear; used especially in runcible spoon "spoon with three short tines like a fork," which first took the name 1926.
runcinate (adj.): 1776, "saw-toothed," from Modern Latin runcinatus, from Latin runcina "a (carpenter's) plane."
rundown (n.): in baseball, 1908, from verbal phrase, from run (v.) + down (adv.). Meaning "list of entries in a horse race and the odds" is from 1935; slang generalized sense of "summary, account, list of information or facts" is from 1945.
rune (n.): Old English run, rune "secret, mystery, dark mysterious statement, (secret) council," also "a runic letter" (runstæf), from Proto-Germanic *runo (source also of Old Norse run "a secret, magic sign, runic character," Old High German runa "a secret conversation, whisper," Gothic runa), from PIE *ru-no-, source of technical terms of magic in Germanic and Celtic (source also of Gaelic run "a secret, mystery, craft, deceit, purpose, intention, desire," Welsh rhin "a secret, charm, virtue"). Also see Runnymede.

The presumption often is that the magical sense was the original one of the word, and the use of runes as letters was secondary. However, this derivation is questioned by some linguists: "[T]he obsession with magic of many runologists can be explained more from the psychology of the scholars than from the intrinsic contents of the inscriptions. ... [F]or almost all [of these scholars] the aura of mystery which they ascribe to the fuþark was a supplementary attraction in an otherwise austere field of labor" [French scholar Lucien Musset, quoted in Elmer H. Antonsen, "The Runes: The Earliest Germanic Writing System," in "The Origins of Writing,"University ogf Nebraska, 1989] .

The word entered Middle English as roun and by normal evolution would have become Modern English *rown, but it died out mid-15c. when the use of runes did. The modern usage is from late 17c., from German philologists who had reintroduced the word in their writings from a Scandinavian source (such as Danish rune, from Old Norse run). The runic alphabet is believed to have developed by 2c. C.E. from contact with Greek writing, with the letters modified to be more easily cut into wood or stone.
rung (n.): Old English hrung "rod, bar," from Proto-Germanic *khrungo (source also of Middle Low German runge, Old High German runga "stake, stud, stave," German Runge "stake, stud, stave," Middle Dutch ronghe, Dutch rong "rung," Gothic hrugga "staff"), of unknown origin with no connections outside Germanic. Sense in English narrowed to "round or stave of a ladder" (first attested late 13c.), but usage of cognate words remains more general in other Germanic languages.
This [rungs] has generally been considered as a mere corruption of rounds; and people of education use only this latter word. [John Pickering, "A Vocabulary or Collection of Words and Phrases which have been Supposed to be Peculiar to the United States of America," Boston, 1816]
runic (adj.): 1660s, from Modern Latin runicus, from Old Norse run (see rune).
runnel (n.): "rivulet," 1570s, in Hakluyt, alteration of Middle English ryneil, from Old English rinelle, rynel, a diminutive of ryne "a stream" (see run (n.)) with -el (2).
runner (n.): c. 1300, "messenger on foot," agent noun from run (v.). Meaning "one who runs" is early 14c. Meaning "smuggler" first recorded 1721; sense of "police officer" is from 1771. Meaning "rooting stem of a plant" is from 1660s; that of "embroidered cloth for a table" is from 1888.
runner-up (n.): 1842, originally in dog racing, "dog that loses only the final race;" see runner + up. General sense is from 1885.
running (n.): Old English ærning, verbal noun from run (v.); to be in (or out) of the running "among" (or "not among") "the lead competitors in a race" (1863) is a metaphor from horse racing, where make the running "set the pace" is recorded from 1837. Running shoe is from 1884.
running (adj.): present participle adjective from run (v.). Running mate originally was a horse entered in a race to set the pace for another from the same stable who was intended to win (1865); U.S. vice-presidential sense is recorded from 1888. Running dog first recorded 1937, from Chinese and North Korean communist phrases used to describe supposed imperialist lackeys, such as Mandarin zou gou "running dog," on the notion of a dog that runs at its master's command. Running board first attested 1817, in reference to ships and boats; 1907 of cars and trucks.
runny (adj.): 1817, from run (v.) + -y (2).
Runnymede: place in Surrey where the Magna Charta was signed, Middle English Ronimede, literally "meadow on the council island," from Old English runieg "council island," from run in sense of "council" (see rune).