Online Etymology Dictionary

rubber (n.): "thing that rubs" (a brush, cloth, etc.), 1530s, agent noun from rub (v.). The meaning "elastic substance from tropical plants" (short for India rubber) first recorded 1788, introduced to Europe 1744 by Charles Marie de la Condamine, so called because it originally was used as an eraser.
Very useful for erasing the strokes of black lead pencils, and is popularly called rubber, and lead-eater. [entry for Caoutchouc in Howard, "New Royal Encyclopedia," 1788]
Meaning "overshoe made of rubber" is 1842, American English; slang sense of "condom" is by 1930s. Sense of "deciding match" in a game or contest is 1590s, of unknown signification, and perhaps an entirely separate word. Rubber stamp (n.) is from 1881; figurative sense of "institution whose power is formal but not real" is from 1919; the verb in this sense is from 1934. Rubber cement is attested from 1856 (from 1823 as India-rubber cement). Rubber check (one that "bounces") is from 1927.
rubberneck (n.): 1897, "person who is always listening to other people's conversation; person who gazes around him with undue curiosity," from rubber + neck (n.). Popularized with reference to sightseers in automobiles. As a verb from 1896. Related: Rubbernecking (1896); rubbernecker (1934).
rubbers (n.): see rubber (n.).
rubbery (adj.): 1890, from rubber (n.) + -y (2). Related: Rubberiness.
rubbish (n.): c. 1400, robous, from Anglo-French rubouses (late 14c.), of unknown origin. No apparent cognates in Old French; apparently somehow related to rubble (see OED). Spelling with -ish is from late 15c. The verb sense of "disparage, criticize harshly" is first attested 1953 in Australian and New Zealand slang. Related: Rubbished; rubbishing.
rubble (n.): "rough, irregular stones broken from larger masses," late 14c., robeyl, from Anglo-French *robel "bits of broken stone," probably related to rubbish [OED], but also possibly from Old French robe (see rob).
rube (n.): 1896, reub, from shortened form of masc. proper name Reuben (q.v.), which is attested from 1804 as a conventional type of name for a country man.
Rube Goldberg (adj.): 1940, from the U.S. cartoonist Reuben Lucius Goldberg (1883-1970) who devised fantastically complex gadgetry to accomplish simple tasks. His British counterpart was Heath Robinson (1872-1944).
rubella (n.): "German measles," 1883, Modern Latin, literally "rash," from neuter plural of Latin rubellus "reddish," diminutive of ruber "red" (see red (adj.1)).
Rubenesque (adj.): of a woman's body, "rounded and alluringly plump," 1904, of the type characteristic of the paintings of Flemish painter Sir Peter Paul Rubens (1577-1640).
Rubicon (n.): in phrase to cross (or pass) the Rubicon "take a decisive step," 1620s, a reference to a small stream to the Adriatic on the coast of northern Italy which in ancient times formed part of the southern boundary of Cisalpine Gaul; crossed by Caesar Jan. 10, 49 B.C.E., when he left his province to attack Pompey. The name is from Latin rubicundus "ruddy," in reference to the color of the soil on its banks.
rubicund (adj.): "inclining to redness," c. 1500, from Middle French rubicond (14c.), or directly from Latin rubicundus, from rubere "to be red," from ruber "red" (see red (adj.1)). Related: Rubicundity.
Rubik's Cube (n.): 1980, named for teacher Ernö Rubik (b.1944) who patented it in Hungary in 1975.
ruble (n.): unit of the Russian monetary system, 1550s, via French rouble, from Russian rubl', perhaps from Old Russian rubiti "to chop, cut, hew," so called because the original metallic currency of Russia (14c.) consisted of silver bars, from which the necessary amount was cut off; from Proto-Slavic *rub-, from PIE root *reub-, *reup- "to snatch" (see rip (v.)).
rubric (n.): c. 1300, "directions in religious services" (often in red writing), from Old French rubrique, rubriche "rubric, title" (13c.), from Latin rubrica "red ochre, red coloring matter," from ruber, from PIE root *rudhro- (see red). Meaning "title or heading of a book" is from early 15c. Related: Rubrical.
ruby (n.): "clear rich-red variety of corundum," c. 1300, from Old French rubi (12c.), from Medieval Latin rubinus lapis "red stone" (source also of Italian rubino), from Latin rubeus "red," related to ruber (see red). As a color name from 1570s. As an adjective from late 15c. Modern French rubis is not explained; Klein suggests a plural mistaken for singular.
ruche (n.): "frill," 1827, from French ruche, literally "beehive" (13c.), of Celtic origin (compare Breton rusken), from Proto-Celtic *rusca "bark." Related: Ruched; ruching.
rucksack (n.): 1866, from German Rucksack, from Alpine dialect Rück "the back" (from German Rücken; see ridge) + Sack "sack" (see sack (n.1)).
ruckus (n.): 1890, possibly a blend of ruction and rumpus.
ruction (n.): "disturbance," 1825, dialectal or colloquial, of unknown origin. Perhaps from eruption or an altered shortening of insurrection.
rudder (n.): mid-15c. alteration of Middle English rother, from Old English roðor "paddle, oar," from Proto-Germanic *rothru- (source also of Old Frisian roðer, Middle Low German roder, Middle Dutch roeder, Dutch roer, Old High German ruodar, German Ruder "oar"), from *ro- "steer" (see row (v.)) + suffix *-þra, used to form neutral names of tools.

Meaning "broad, flat piece of wood attached to the stern of a boat and guided by a tiller for use in steering" is from c. 1300. For shift of -th- to -d- compare burden (n.1), murder (n.); simultaneous but opposite to the movement that turned -d- to -th- in father (n.), etc.
ruddock (n.): "robin," late Old English rudduc, from rudu "red color," related to read (see red (adj.1)) + diminutive suffix.
ruddy (adj.): late Old English rudig "rubicund," probably from rudu "redness," related to read "red" (see red (adj.1)). As a British slang euphemism for bloody (q.v.), first recorded 1914. Related: Ruddiness.
rude (adj.): late 13c., "coarse, rough" (of surfaces), from Old French ruide (13c.) or directly from Latin rudis "rough, crude, unlearned," a word of uncertain etymology, related to rudus "rubble." The usual preferred derivation is that it is from the same source as Latin rufus "red" (see rufous) via a notion of raw ("red") meat, but de Vaan points out "there is not a shimmer of a meaning 'red' in rudis or in rudus 'rubble', so that the supposed shift from 'crude (meat)' > 'crude' rests in the air."

Sense of "ill-mannered, uncultured; uneducated, uncultured" is from mid-14c. Rude boy (also rudie, for short) in Jamaican slang is attested from 1967. Figurative phrase rude awakening is attested from 1895.
rudely (adv.): mid-14c., from rude (adj.) + -ly (2).
rudesby (n.): "insolent person," 1560s, mock surname from rude + -by, common place-name (and thus surname) ending element, as in Grimsby, Rigby. Similar formations in idlesby "lazy fellow" (1610s), sneaksby "paltry, sneaking fellow" (1570s), suresby (16c.), lewdsby (1590s).
rudiment (n.): 1540s, from Middle French rudiment (16c.) or directly from Latin rudimentum "early training, first experience, beginning, first principle," from rudis "unlearned, untrained" (see rude). Related: Rudiments.
rudimentary (adj.): 1827; see rudiment + -ary. Earlier was rudimental (1590s).
Rudolph: masc. proper name, from German Rudolf, from Old High German Hrodulf, literally "fame-wolf," from hruod- "fame, glory" + wolf.
Rudra: storm god in Vedic mythology, from Sanskrit Rudrah, according to Klein literally "the howler, roarer," from stem of rudati "weeps, laments, bewails," cognate with Latin rudere "to roar, bellow," Lithuanian rauda "wail, lamentation," Old English reotan "to wail, lament."
rue (v.): "feel regret," Old English hreowan "make sorry, distress, grieve" (class II strong verb; past tense hreaw, past participle hrowen), from Proto-Germanic *khrewan (source also of Old Frisian riowa, Middle Dutch rouwen, Old Dutch hrewan, German reuen "to sadden, cause repentance"); in part, blended with Old English weak verb hreowian "feel pain or sorrow," and perhaps influenced by Old Norse hryggja "make sad," both from Proto-Germanic *khruwjan, all from PIE root *kreue- (2) "to push, strike" (see anacrusis). Related: Rued; ruing.
rue (n.1): perennial evergreen shrub, late 14c., from Old French rue (13c.), earlier rude, from Latin ruta "rue," probably from Greek rhyte, of uncertain etymology, originally a Peloponnesian word. The bitter taste of its leaves led to many punning allusions to rue (n.2.).
rue (n.2): "sorrow, repentance," Old English hreow "grief, repentance, sorrow, regret, penitence," common Germanic (Frisian rou, Middle Dutch rou, Dutch rouw, Old High German (h)riuwa, German reue), related to the root of rue (v.).
rue (n.3): French for "street," from Vulgar Latin *ruga (source also of Old Italian ruga, Spanish rua "street in a village"), from Latin ruga, properly "a furrow," then in Medieval Latin "a path, street," from PIE root *reue- (2) "to smash, knock down, tear out, dig up" (see rough (adj.)).
rueful (adj.): early 13c., rewfulle, reowfule, from rue (n.2) + -ful. Related: Ruefulness.
ruefully (adv.): early 13c., reufulike; see rueful + -ly (2).
ruff (n.): kind of large collar, stiffly starched, especially common in the seventeenth century, 1520s, originally in reference to sleeves (of collars, from 1550s), probably a shortened form of ruffle.

Card-playing sense is a separate word, from a former game of that name (1580s), from Middle French roffle, earlier romfle (early 15c.), from Italian ronfa, perhaps a corruption of trionfo "triumph" (from French; compare trump). The game was in vogue c. 1590-1630.
ruff (v.): in cards, 1760, from ruff (n.). Related: Ruffed; ruffing.
ruffian (n.): 1530s, "a boisterous, brutal fellow, one ready to commit any crime," from Middle French rufian "a pimp" (15c.), from Italian ruffiano "a pander, pimp," of uncertain origin, perhaps from a Germanic source related to rough (adj.), but Dutch roffiaan, German Ruffian are said to be from French. English meaning might have been influenced by similarity of sound to rough. Related: Ruffianly.

The Romanic words (such as Medieval Latin ruffianus, Provençal rufian, Catalan rufia, Spanish rufian) preserve the sense of "protector or owner of whores." For sense evolution in English, compare bully (n.).
ruffle (v.): early 14c., "to disturb the smoothness of," perhaps from Old Norse hrufla "to scratch," or Low German ruffelen "to wrinkle, curl," both of unknown origin. Meaning "disarrange" (hair or feathers) first recorded late 15c.; sense of "annoy, distract" is from 1650s. Related: Ruffled; ruffling.
ruffle (n.): "ornamental frill," 1707, from ruffle (v.).
rufous (adj.): "reddish-brown," 1782, from Latin rufus "red, reddish, tawny, red-haired," from an Osco-Umbrian cognate of Latin ruber "red" (see red (adj.1)).
Rufus: masc. proper name, literally "red-haired," from Latin rufus "red, tawny, red-haired" (see rufous).
rug (n.): 1550s, "coarse fabric," of Scandinavian origin; compare Norwegian dialectal rugga "coarse coverlet," from Old Norse rogg "shaggy tuft," from Proto-Germanic *rawwa-, perhaps related to rag (n.) and rough (adj.). Sense evolved to "coverlet, wrap" (1590s), then "mat for the floor" (1808). Meaning "toupee" is theater slang from 1940. Cut a rug "dance" is slang first attested 1942. To sweep (something) under the rug in the figurative sense is from 1954. Figurative expression pull the rug out from under (someone) "suddenly deprive of important support" is from 1936, American English. Earlier in same sense was cut the grass under (one's) feet (1580s).
rugae (n.): plural of ruga (1775), from Latin ruga "a wrinkle in the face," from PIE *rug-, variant of *reue- (2) "to smash, knock down, tear up, dig up, uproot" (see rough (adj.)).
rugby (n.): type of football, 1864, after Rugby, public school where the game was played, from city of Rugby in Warwickshire, central England. The place name is Rocheberie (1086), probably "fortified place of a man called *Hroca;" with second element from Old English burh (dative byrig), replaced by 13c. with Old Norse -by "village" due to the influence of Danish settlers. Otherwise it might be *Rockbury today. Or first element perhaps is Old English hroc "rook." Rugby Union formed 1871. Slang rugger for "rugby" is from 1893.
rugged (adj.): c. 1300, "rough, shaggy, careworn" (originally of animals), from Old Norse rogg "shaggy tuft" (see rug). "The precise relationship to ragged is not quite clear, but the stem is no doubt ultimately the same" [OED]. Meaning "vigorous, strong, robust" is American English, by 1848.
We were challenged with a peace-time choice between the American system of rugged individualism and a European philosophy of diametrically opposed doctrines -- doctrines of paternalism and state socialism. [Herbert Hoover, speech in New York, Oct. 22, 1928]
Hoover said the phrase was not his own, and it is attested from 1897, though not in a patriotic context. Related: Ruggedly; ruggedness.
rugrat (n.): also rug-rat, "baby, child," by 1968; see rug + rat (n.).
ruin (n.): late 14c., "act of giving way and falling down," from Old French ruine "a collapse" (14c.), and directly from Latin ruina "a collapse, a rushing down, a tumbling down" (source also of Spanish ruina, Italian rovina), related to ruere "to rush, fall violently, collapse," from PIE *reue- (2) "to smash, knock down, tear out, dig up" (see rough (adj.)). Meaning "complete destruction of anything" is from 1670s. Ruins "remains of a decayed building or town" is from mid-15c.; the same sense was in the Latin plural noun.
ruin (v.): 1580s (transitive), from ruin (n.). Intransitive sense "fall into ruin" is from c. 1600. Financial sense is attested from 1660. Related: Ruined; ruining.