Online Etymology Dictionary

rickettsia (n.): parasitic organism, 1919, named 1916 in Modern Latin by H. da Rocha-Lima in honor of U.S. pathologist H.T. Ricketts (1871-1910), who first identified it in 1909 and died of typhus as a result of his contact with it. The bacteria causes typhus and Rocky Mountain spotted fever, but is unrelated by pathology or etymology to rickets (q.v.), which is the result of vitamin D deficiency.
rickety (adj.): "liable to fall down," 1680s, from rickets (with + -y (2)), via notion of "weak, unhealthy." Literal sense is from c.1720 but never common in English. Of material things, from 1799.
rickey (n.): alcoholic drink made with carbonated water and lime juice, 1895; reputedly from the name of Col. Joe Rickey of St. Louis, Missouri.
rickshaw (n.): 1887, shortened form of jinrikisha, popularized by Kipling, from Japanese jin "a man" + riki "power" + sha "carriage."
ricochet (v.): 1758, originally in a military sense, from French ricochet (n.) "the skipping of a shot, or of a flat stone on water," in earliest use only in phrase fable du ricochet, an entertainment in which the teller of a tale skillfully evades questions, and chanson du ricochet, a kind of repetitious song; of uncertain origin. The noun is attested from 1769.
ricotta (n.): kind of Italian cottage cheese, 1879, earlier ricoct (1580s), from Italian ricotta, literally "recooked," from fem. past participle of Latin recoquere.
rid (v.): c.1200, from Old Norse ryðja (past tense ruddi, past participle ruddr) "to clear (land) of obstructions," from Proto-Germanic *reudijanan (cf. Old High German riuten, German reuten "to clear land," Old Frisian rothia "to clear," Old English -royd "clearing," common in northern place names). The general sense of "to make (something) free (of something else)" emerged by 1560s. Senses merged somewhat with Northern English, Scottish, and U.S. dialectal redd.
riddance (n.): 1530s, from rid + -ance.
ridden (adj.): mid-14c., from past participle of ride (q.v.). Sense evolution, via horses, from "that which has been ridden upon, broken in" (1520s) to, in compounds, "oppressed, taken advantage of" (1650s).
riddle (n.): "A word game or joke, comprising a question or statement couched in deliberately puzzling terms, propounded for solving by the hearer/reader using clues embedded within that wording" [Oxford Dictionary of English Folklore], Old English rædels "opinion, riddle, counsel, conjecture," from Proto-Germanic *rædislijan (cf. Old Saxon radisli, Middle Dutch raetsel, Dutch raadsel, Old High German radisle, German Rätsel "riddle"). Related to Old English rædan "to advise, counsel, read, guess" (see read (v.)).
riddle (v.): "perforate with many holes," 1817 (implied in riddled), earlier "sift" (early 13c.), from Middle English ridelle "coarse sieve," from late Old English hriddel "sieve," altered by dissimilation from Old English hridder "sieve," from Proto-Germanic *khridan (cf. German Reiter), from *khrid- "shake" (cf. Old Norse hreinn, Old High German hreini, Gothic hrains "clean, pure"); probably from same PIE root as Latin cribrum "sieve, riddle," Greek krinein "to separate, distinguish, decide" (see crisis).
ride (v.): Old English ridan "ride" (as on horseback), "move forward, rock" (class I strong verb; past tense rad, past participle riden), from Proto-Germanic *ridanan (cf. Old Norse riða, Old Frisian rida, Middle Dutch riden, German reiten), from PIE *reidh- "to ride" (cf. Old Irish riadaim "I travel," Old Gaulish reda "chariot").

Meaning "heckle" is from 1912; that of "have sex with (a woman)" is from mid-13c.; that of "dominate cruelly" is from 1580s. To ride out "endure (a storm, etc.) without great damage" is from 1520s. To ride shotgun is 1963, from Old West stagecoach custom in the movies. To ride shank's mare "walk" is from 1846.
ride (n.): 1759, from ride (v.); slang meaning "a motor vehicle" is recorded from 1930; sense of "amusement park device" is from 1934. To take (someone) for a ride "tease, mislead, cheat," is first attested 1925, American English, possibly from underworld sense of "take on a car trip with intent to kill" (1927). Phrase go along for the ride in the figurative sense "join in passively" is from 1956. A ride cymbal (1956) is used by jazz drummers for keeping up continuous rhythm, as opposed to a crash cymbal (ride as "rhythm" in jazz slang is recorded from 1936).
rider (n.): "one who rides," Old English ridere, agent noun from ride (v.). Meaning "clause tacked on to a document after first draft" is from 1660s.
ridge (n.): Old English hrycg "back of a man or beast," probably reinforced by Old Norse hryggr "back, ridge," from Proto-Germanic *khrugjaz (cf. Old Frisian hregg, Old Saxon hruggi, Dutch rug, Old High German hrukki, German Rücken "the back"), of uncertain origin. Also in Old English, "the top or crest of anything," especially when long and narrow. The connecting notion is of the "ridge" of the backbone. Ridge-runner "Southern Appalachian person" first recorded 1917.
ridicule (v.): 1680s, from French ridicule, from Latin ridiculum, neuter of ridiculus (see ridiculous). Related: Ridiculed; ridiculing.
ridicule (n.): 1700, from ridicule (v.).
"He who brings ridicule to bear against truth, finds in his hand a blade without a hilt." [Walter Savage Landor, "Imaginary Conversations"]
ridiculous (adj.): 1540s, from Latin ridiculosus "laughable," from ridiculus "that which excites laughter," from ridere "to laugh."
riding (n.): one of the three districts into which Yorkshire was divided, late 13c., from late Old English *þriðing, a relic of Viking rule, from Old Norse ðriðjungr "third part," from ðriði "third" (see third). The initial consonant merged with final consonant of preceding north, west, or east.
Riesling: 1833, from German Riesling (15c.), of uncertain origin.
rife (adj.): Old English rife "abundant." Related to Old Norse rifr (Swedish river, Norwegian riv), Middle Dutch riif, Middle Low German rive "abundant, generous." "The prevalence of the word in early southern texts is in favour of its being native in English, rather than an adoption from Scandinavian." [OED]
riff (n.): "melodic phrase in jazz," 1935 (but said to have been used by musicians since c.1917), of uncertain origin, perhaps a shortened form of riffle, or altered from refrain. The verb is attested from 1942. Related: Riffed; riffing.
riffle (v.): 1754, "to make choppy water," American English, perhaps a variant of ruffle "make rough." The word meaning "shuffle" (cards) is first recorded 1894, probably echoic; that of "skim, leaf through quickly" is from 1922.
riffraff (n.): late 15c., from earlier rif and raf "one and all, every scrap" (mid-14c.), from Old French rif et raf, from rifler "to spoil, strip" (see rifle (v.)) and raffler "carry off," related to rafle "plundering" (see raffle).
rifle (n.): 1775, "portable firearm having a spirally grooved bore," used earlier of the grooves themselves (1751), noun use of rifled (pistol), 1680s, from verb meaning "to cut spiral grooves in" (a gun barrel), 1630s, probably from French rifler, from Old French rifler "to scratch or groove" (see rifle (v.)).
rifle (v.): "to plunder," early 14c. (implied in rifling), from Old French rifler "strip, plunder," literally "to graze, scratch," probably from a Germanic source (cf. Old English geriflian "to wrinkle," Old High German riffilon "to tear by rubbing," Old Norse rifa "to tear, break"). Related: Rifled; rifling.
rift (n.): c.1300, from a Scandinavian source (cf. Danish and Norwegian rift "a cleft," Old Icelandic ript (pronounced "rift") "breach;" related to Old Norse ripa "to break a contract" (see riven).
rig (v.): late 15c., originally nautical, "to fit with sails," probably from a Scandinavian source (cf. Danish, Norwegian rigge "to equip," Swedish rigga "to rig"), though these may be from English. Slang meaning "to pre-arrange or tamper with results" is attested from 1938. Related: Rigged; rigging.
rig (n.): "distinctive arrangement of sails, masts, etc. on a ship," 1822, from rig (v.); extended to horse vehicles (1831), which led to sense of "truck, bus, etc." (1851).
Rig veda: 1776, from Sanskrit rigveda, from rg- "song, praise, knowledge" + veda "knowledge." A thousand hymns, orally transmitted, probably dating from before 1000 B.C.E.
rigatoni (n.): "short, hollow, fluted tubes of pasta," 1930, from Italian rigatooni, plural of rigato, past participle of rigare "to draw a line, to make fluting."
Rigel: bright star in Orion, 1590s, from Arabic Rijl Jauzah al Yusra "the Left Leg of the Central One," from rijl "foot."
right (adj.1): "morally correct," Old English riht "just, good, fair, proper, fitting, straight," from Proto-Germanic *rekhtaz (cf. Old High German reht, German recht, Old Norse rettr, Gothic raihts), from PIE root *reg- "move in a straight line," also "to rule, to lead straight, to put right" (see regal; cf. Greek orektos "stretched out, upright;" Latin rectus "straight, right;" Old Persian rasta- "straight, right," aršta- "rectitude;" Old Irish recht "law;" Welsh rhaith, Breton reiz "just, righteous, wise").

Cf. slang straight "honest, morally upright," and Latin rectus "right," literally "straight," Lithuanian teisus "right, true," literally "straight." Greek dikaios "just" (in the moral and legal sense) is from dike "custom."

As an emphatic, meaning "you are right," it is recorded from 1580s; use as a question meaning "am I not right?" is from 1961. The sense in right whale is "justly entitled to the name." Phrase right off the bat is 1888, also hot from the bat (1888), probably a baseball metaphor, but cricket is possible as a source; there is an early citation from Australia (in an article about slang): "Well, it is a vice you'd better get rid of then. Refined conversation is a mark of culture. Let me hear that kid use slang again, and I'll give it to him right off the bat. I'll wipe up the floor with him. I'll ---" ["The Australian Journal," November 1888].

Right stuff "best human ingredients" is from 1848, popularized by Tom Wolfe's 1979 book about the first astronauts. Right on! as an exclamation of approval first recorded 1925 in black slang, popularized mid-1960s by Black Panther movement. Right of way is attested from 1768.
right (adj.2): "opposite of left," early 12c., riht, from Old English riht, which did not have this sense but meant "good, proper, fitting, straight" (see right (adj.1)). The notion is of the right hand as the "correct" hand. The usual Old English word for this was swiþra, literally "stronger." "The history of words for 'right' and 'left' shows that they were used primarily with reference to the hands" [Buck]. Cf. similar sense evolution in Dutch recht, German recht "right (not left)," from Old High German reht, which meant only "straight, just."

The usual PIE root (*dek-) is represented by Latin dexter (see dexterity). Other derivations on a similar pattern to English right are French droit, from Latin directus "straight;" Lithuanian labas, literally "good;" and Slavic words (Bohemian pravy, Polish prawy, Russian pravyj) from Old Church Slavonic pravu, literally "straight," from PIE *pro-, from root *per- (1) "forward, through" (see per).

The political sense of "conservative" is first recorded 1794 (adj.), 1825 (n.), a translation of French Droit "the Right, Conservative Party" in the French National Assembly (1789; see left (adj.)).
right (v.): Old English rihtan "to straighten, rule, set up," from riht (adj.); see right (adj.1). Cf. Old Norse retta "to straighten," German richten, Gothic garaihtjan. Related: Righted; righting.
right (n.): Old English riht (West Saxon, Kentish), reht (Anglian), "that which is morally right," also "rule of conduct; law of a land;" also "what someone deserves; a just claim; a legal entitlement." Also "the right" (as opposed to the left), from the root of right (adj.1). From early 14c. as "a right action, a good deed." The phrase to rights "at once, straightway" is 1660s, from sense "in a proper manner" (Middle English).
right hand: figurative for "indispensable person," 1520s; right-hand man first attested 1660s.
right wing: as a noun, in the political sense, 1905 (see left). From 1882 in football. Right-winger attested by 1919 in U.S. politics, 1895 in sports.
righteous (adj.): early 16c. alteration of rightwise, from Old English rihtwis, from riht (see right) + wis "wise, way, manner." Suffix altered by influence of courteous, etc. Meaning "genuine, excellent" is c.1900 in jazz slang. Related: Righteousness.
rightful: Old English rihtful; see right (adj.1) + -ful. Related: Rightfully.
rigid (adj.): 1530s, from Latin rigidus "hard, stiff, rough, severe," from rigere "be stiff," from PIE *reig- "stretch (tight), bind tightly, make fast" (cf. Old Irish riag "torture," Middle High German ric "band, string").
rigmarole (n.): 1736, "a long, rambling discourse," from an altered, Kentish colloquial survival of ragman roll "long list or catalogue" (1520s), in Middle English a long roll of verses descriptive of personal characters, used in a medieval game of chance called Rageman, perhaps from Anglo-French Ragemon le bon "Ragemon the good," which was the heading on one set of the verses, referring to a character by that name. Sense transferred to "foolish activity or commotion" by 1939.
rigor (n.): late 14c., from Old French rigor (13c.), from Latin rigorem (nominative rigor) "numbness, stiffness, rigor," from rigere "be stiff" (see rigid).
rigor mortis: 1837, from Latin rigor "stiffness" (see rigor) + mortis, genitive of mors "death" (see mortal).
rigorous (adj.): late 14c., from Old French rigorous (Modern French rigoureux), from Medieval Latin rigorosus, from Latin rigor (see rigor). Related: Rigorously.
rile (v.): 1825, American English spelling alteration to reflect a dialectal pronunciation of roil (q.v.); cf. heist from hoist. Related: Riled; riling.
rill (n.): "small brook, rivulet," 1530s, from Dutch ril, Low German rille "groove, furrow, running stream," probably from Proto-Germanic *riðele (cf. Old English rið, riþe "brook, stream," which survives only in obscure English dialects), a diminutive form from PIE root *reie- "to run, flow" (see Rhine).
rim (n.): Old English rima "edge, border," as in særima "seashore," literally "rim of the sea," and dægrima "dawn," literally "rim of the day." Related to Old Norse rime, rimi "a raised strip of land, ridge." No known cognates in other languages. The snare drummer's rim shot is recorded from 1934.
rime (n.): "hoarfrost," Old English hrim, from Proto-Germanic *khrima- (cf. Old Norse hrim, Dutch rijm, German Reif). Old French rime is of Germanic origin. Rare in Middle English, surviving mainly in Scottish and northern English, revived in literary use late 18c.
rind (n.): Old English rinde "bark, crust," later "peel of a fruit or vegetable" (c.1400), from Proto-Germanic *rendo- (cf. Old Saxon rinda, Middle Dutch rinde, German Rinde), related to Old English rendan "to rend."