Online Etymology Dictionary

Robinson Crusoe: "man without companionship," 1768, from the eponymous hero of Daniel Defoe's fictional shipwreck narrative (1719).
robot (n.): 1923, from English translation of 1920 play "R.U.R." ("Rossum's Universal Robots"), by Karel Capek (1890-1938), from Czech robotnik "forced worker," from robota "forced labor, compulsory service, drudgery," from robotiti "to work, drudge," from an Old Czech source akin to Old Church Slavonic rabota "servitude," from rabu "slave," from Old Slavic *orbu-, from PIE *orbh- "pass from one status to another" (see orphan). The Slavic word thus is a cousin to German Arbeit "work" (Old High German arabeit). According to Rawson the word was popularized by Karel Capek's play, "but was coined by his brother Josef (the two often collaborated), who used it initially in a short story."
robotic (adj.): 1941 (Asimov), from robot + -ic.
robotics (n.): 1941, from robot + -ics. Coined in a science fiction context by Russian-born U.S. author Isaac Asimov (1920-1992), who proposed the "Three Laws of Robotics" in 1968.
robust (adj.): 1540s, from Middle French robuste (14c.) and directly from Latin robustus "strong and hardy," literally "as strong as oak," originally "oaken," from robur, robus "hard timber, strength," also "a special kind of oak," named for its reddish heartwood, from Latin ruber "red" (related to robigo "rust"), from PIE *reudh- (see red (adj.1)). Related: Robustly; robustness. Robustious (1540s) was a common form in 17c. (see "Hamlet" iii.2); it fell from use by mid-18c., but was somewhat revived by mid-19c. antiquarian writers.
roc (n.): large, ferocious bird of fable, 1570s, from Arabic rukhkh, from Persian rukh. Mentioned in Marco Polo's account of Madagascar, modern use is mostly from "Arabian Nights." Hence roc's egg "something marvelous or prodigious."
rock (n.1): "stone, mass of mineral matter," c. 1300, from Old English rocc (as in stanrocc "stone rock or obelisk") and directly from Old North French roque, which is cognate with Medieval Latin rocca (8c.), from Vulgar Latin *rocca, of uncertain origin, according to Klein sometimes said to be from Celtic (compare Breton roch).

In Middle English it seems to have been used principally for rock formations as opposed to individual stones. Meaning "precious stone, especially a diamond," is 1908, U.S. slang. Meaning "crystallized cocaine" is attested from 1973, in West Coast U.S. slang. Figurative use for "sure foundation" (especially with reference to Christ) is from 1520s; but also from 1520s as "source of danger or destruction," in reference to shipwrecks (as in on the rocks). Also used attributively in names of animals that frequent rocky habitats, as in rock lobster (1843). Between a rock and a hard place first attested 1921:
to be between a rock and a hard place, vb. ph. To be bankrupt. Common in Arizona in recent panics; sporadic in California. ["Dialect Notes," vol. V, part iv, 1921]
Rock-ribbed is from 1776, originally of land; figurative sense of "resolute" first recorded 1887. Rock-happy (1945) was U.S. Pacific Theater armed forces slang for "mentally unhinged after too much time on one island." The rock-scissors-paper game is attested by that name from 1976; from 1968 as paper-stone-scissors. A 1967 source says it is based on Japanese Jan Ken Pon (or Janken for short), which is said to mean the same thing more or less.
rock (v.1): "to sway," late Old English roccian "move a child gently to and fro," related to Old Norse rykkja "to pull, tear, move," Swedish rycka "to pull, pluck," Middle Dutch rucken, Old High German rucchan, German rücken "to move jerkily."

Meaning "cause to sway back and forth" is from late 13c. Intransitive sense from late 14c. For popular music senses, see rock (v.2). Related: Rocked; rocking. To rock the boat in the figurative sense "stir up trouble" is from 1914. Rock-a-bye first recorded 1805 in nursery rhyme.
rock (v.2): "to dance to popular music with a strong beat," 1948 (first attested in song title "We're gonna rock"), from rock (v.1), in earlier blues slang sense of "to cause to move with musical rhythm" (1922); often used at first with sexual overtones (as in 1922 song title "My Man Rocks Me (with One Steady Roll)"). Sense developed early 1950s to "play or dance to rock and roll music." Related: Rocked; rocking. Rocksteady, Jamaican pop music style (precursor of reggae), is attested from 1969.
rock (n.2): "action of rocking; a movement to and fro," 1823, from rock (v.1). As short for rock and roll, by 1957; but sense of "musical rhythm characterized by a strong beat" is from 1946, in blues slang. Rock star attested by 1966.
rock and roll (n.): also rock 'n' roll, 1954 in reference to a specific style of popular music, from rock (v.2) + roll (v.). The verbal phrase had been an African-American vernacular euphemism for "sexual intercourse," used in popular dance music lyrics and song titles since at least the 1930s.
rock-bottom (adj.): "lowest possible," 1884, from noun (1815), from rock (n.1) + bottom (n.).
rock-candy (n.): 1723, from rock (n.1) + candy (n.).
rock-face (n.): 1847, from rock (n.1) + face (n.).
rock-garden (n.): 1819, from rock (n.1) + garden (n.).
rock-hound (n.): 1921, from rock (n.1) + hound (n.). Used variously of geologists, mineralogists, and amateur collectors.
rock-salt (n.): 1707, from rock (n.1) + salt (n.).
rockabilly (n.): 1956, from noun sense of rock (n.2) in the music sense + second element abstracted from hillbilly music. One of the first uses is in a "Billboard" item about Johnny Burnette's "Lonesome Train."
Rockefeller (n.): "immensely rich man," 1938, in reference to U.S. financier and philanthropist John D. Rockefeller (1839-1937).
rocker (n.): "a rocking chair," 1852, American English, from rock (v.1); earlier "nurse charged with rocking a cradle" (early 14c.). In sense of "one of the curved pieces of wood that makes a chair or cradle rock" it dates from 1787. Slang off (one's) rocker "crazy" first recorded 1897. Meaning "one who enjoys rock music" (as opposed to mod (n.1)) is recorded from 1963, from rock (v.2).
rocket (n.1): garden plant of the cabbage family, c. 1500, from Middle French roquette (16c.), from Italian rochetta, diminutive of ruca "a kind of cabbage," from Latin eruca "colewort," perhaps so called for its downy stems and related to ericus "hedgehog," also "a beam set with spikes," from PIE *ghers- "to bristle" (see horror).
rocket (n.2): type of self-propelling projectile, 1610s, from Italian rocchetto "a rocket," literally "a bobbin," diminutive of rocca "a distaff," so called because of cylindrical shape. The Italian word probably is from a Germanic source (compare Old High German rocko "distaff," Old Norse rokkr), from Proto-Germanic *rukkon-, from PIE root *rug- "fabric, spun yarn."

Originally "fireworks rocket," meaning "device propelled by a rocket engine" first recorded 1919; rocket-ship in the modern sense first attested February 1927 ("Popular Science"); earlier as a type of naval warship firing projectiles. Rocket science in the figurative sense of "difficult, complex process or topic" is attested by 1985. Rocket scientist is from 1952.
That such a feat is considered within the range of possibility is evidenced by the activities of scientists in Europe as well as in America. Two of them, Prof. Herman Oberth and Dr. Franz Hoeff, of Vienna, are constructing a five-ton rocket ship in which they hope to reach the moon in two days. ["Popular Science," Feb. 1927]
rocket (v.): "to spring like a rocket," 1860, from rocket (n.2). Earlier "to attack with rockets" (1799). Related: Rocketed; rocketing.
rocketry (n.): 1930, from rocket (n.2) + -ry.
Rockies (n.): "the Rocky Mountains," 1827; see rocky.
rocking (adj.): "moving back and forth or to and fro," late 14c., present participle adjective from rock (v.1). Of music, from 1949 (see rock (v.2)). Rocking-horse is first recorded 1724; rocking-chair is from 1766.
rocks (n.): plural of rock (n.1). Meaning "ice cubes" is from 1946; slang meaning "testicles" is first recorded in phrase get (one's) rocks off "achieve intense satisfaction." On the rocks "ruined" is from 1889, figurative use of the expression with reference to ships (by 1735).
rocky (adj.): "full of rocks," c. 1400, from rock (n.1) + -y (2); "unsteady," 1737, from rock (v.1). Meaning "difficult, hard" is recorded from 1873, and may represent a bit of both.

The Rocky Mountains so called by 1802, translating French Montagnes Rocheuses, first applied to the Canadian Rockies. "The name is not directly self-descriptive but is an approximate translation of the name of the former Native American people here known as the Assiniboin .... The mountains are in fact not noticeably rocky" [Room]. Bright notes that "These Indians were called /assiniipwaan/, lit. 'stone Sioux', by their Cree (Algonkian) neighbors".
rococo (adj.): 1836, "old-fashioned," from French rococo (19c.), apparently a humorous alteration of rocaille "shellwork, pebble-work" from Middle French roche "rock," from Vulgar Latin *rocca "stone." Specifically of furniture or architecture of the time of Louis Quatorze and Louis Quinze, from 1841. If this is correct, the reference is to the excessive use of shell designs in this lavish style. For differentiation, see baroque. The general sense of "tastelessly florid or ornate" is from 1844.
Much of the painting, engraving, porcelain-work, etc., of the time has ... a real decorative charm, though not of a very high order in art. Hence rococo is used attributively in contempt to note anything feebly pretentious and tasteless in art or literature. [Century Dictionary, 1902]
rod (n.): Old English rodd "a rod, pole," which is probably cognate with Old Norse rudda "club," from Proto-Germanic *rudd- "stick, club," from PIE *reudh- "to clear land."

As a long, tapering elastic pole for fishing, from mid-15c. Figurative sense of "offshoot" (mid-15c.) led to Biblical meaning "scion, tribe." As an instrument of punishment, attested from mid-12c.; also used figuratively for "any sort of correction or punishment," but the basic notion is of beating someone with a stick.

As a unit of measure (5½ yards or 16½ feet, also called perch or pole) first attested mid-15c., from the stick used to measure it off. As a measure of area, "a square perch," from late 15c., the usual measure in brickwork. Meaning "light-sensitive cell in a retina" is from 1866, so-called for its shape. Slang meaning "penis" is recorded from 1902; that of "gun, revolver" is from 1903.
rode: past tense of ride (q.v.).
rodent (n.): 1835 (as an adjective 1833), from Modern Latin Rodentia, the order name, from Latin rodentem (nominative rodens), present participle of rodere "to gnaw, eat away," from PIE root *red- "to scrape, scratch, gnaw" (source also of Sanskrit radati "scrapes, gnaws," radanah "tooth;" Latin radere "to scrape;" Welsh rhathu "scrape, polish"). Uncertain connection to Old English rætt (see rat (n.)).
rodeo (n.): 1914 as public entertainment show of horse-riding skill, from earlier meaning "cattle round-up" (1834), from Spanish rodeo, "pen for cattle at a fair or market," literally "a going round," from rodear "go round, surround," related to rodare "revolve, roll," from Latin rotare "go around" (see rotary).
Roderick: also Roderic, masc. proper name, from Old High German Hroderich, literally "ruling in fame," from hruod- "fame, glory" + Proto-Germanic *rikja "rule" (see rich). Italian and Spanish Rodrigo, Russian Rurik are from German.
rodomontade (n.): 1610s (earlier rodomontado, 1590s), "vain boasting like that of Rodomonte," character in Ariosto's "Orlando Furioso." In dialectal Italian the name means literally "one who rolls (away) the mountain."
roe (n.1): "fish eggs," mid-15c., probably from an unrecorded Old English *hrogn, from Proto-Germanic *khrugna (source also of Old Norse hrogn, Danish rogn, Swedish rom, Flemish rog, Middle Low German and Middle Dutch roge, Old High German rogo, German Rogen "roe"), from PIE *krek- "frog spawn, fish eggs" (source also of Lithuanian kurkle, Russian krjak "spawn of frogs"). Exact relations of the Germanic words are uncertain.
roe (n.2): "small deer," Old English ra, from raha, from Proto-Germanic *raikhaz (source also of Old Norse ra, Old Saxon reho, Middle Dutch and Dutch ree, Old High German reh, German Reh "roe"), of uncertain origin; perhaps from PIE root *rei- "streaked, spotted, striped in various colors."
roebuck (n.): c. 1200, from roe (n.2) + buck (n.1). Similar formation in Dutch reebok, German Rehbock, Danish raabuck.
roentgen: 1896, in Roentgen rays "X-rays," in recognition of German physicist Wilhem Conrad Röntgen (1845-1923), who discovered X-rays in 1895. As a unit of exposure to radiation, it is attested from 1922, proposed in French in 1921.
rofl: by 1993, online chat abbreviation for rolling on the floor laughing.
rogation (n.): late 14c., from Latin rogationem (nominative rogatio) "an asking, prayer, entreaty," noun of action from past participle stem of rogare "to ask, question, propose, request," apparently a figurative use and meaning literally "to stretch out (the hand)," from PIE *rog-, variant of the root *reg- "move in a straight line" (see regal). Related: Rogations.

Rogation days were the Monday, Tuesday and Wednesday before Ascension Day, a time for processions round fields blessing crops and praying for good harvest, also blessing the boundary markers of each parish. Discouraged by Protestants as superstitious, but continued or revived in modified form as beating the bounds.
Roger: masc. proper name, from Old French Rogier, from Old High German Hrotger, literally "famous with the spear," from hruod- "fame, glory" + ger "spear" (see gar (n.)). As a generic name for "a person," attested from 1630s. Slang meaning "penis" was popular c. 1650-c. 1870; hence the slang verb sense of "to copulate with (a woman)," attested from 1711.

The use of the word in radio communication to mean "yes, I understand" is attested from 1941, from the U.S. military phonetic alphabet word for the letter -R-, in this case an abbreviation for "received." Said to have been used by the R.A.F. since 1938. The Jolly Roger pirate flag is first attested 1723, of unknown origin; jolly here has its otherwise obsolete sense "high-hearted, gallant." Roger de Coverley, once a favorite English country dance, is so called from 1685, in reference to Addison's character in the "Spectator." French roger-bontemps "jovial, carefree man," is attested there from 15c.
Roget: in reference to the "Thesaurus of English Words and Phrases" published 1852 by English physician and philologist Peter Mark Roget (1779-1869). Related: Roget's.
rogue (n.): 1560s, "idle vagrant," perhaps a shortened form of roger (with a hard -g-), thieves' slang for a begging vagabond who pretends to be a poor scholar from Oxford or Cambridge, which is perhaps an agent noun in English from Latin rogare "to ask." Another theory [Klein] traces it to Celtic (compare Breton rog "haughty"); OED says, "There is no evidence of connexion with F. rogue 'arrogant.' "

In playful or affectionate use, "one who is mischievous," 1590s. Meaning "large wild beast living apart from the herd" is from 1859, originally of elephants. Meaning "something uncontrolled or undisciplined" is from 1964. Also common in 17c. as a verb. Rogue's gallery "police collection of mug shots" is attested from 1859.
roguery (n.): 1590s, from rogue (n.) + -ery.
roguish (adj.): 1570s, from rogue + -ish. Related: Roguishly; roguishness.
Rohypnol (n.): 1995, trade name for a powerful insomnia drug.
roil (v.): 1580s, of uncertain origin, probably from Middle French rouiller "to rust, make muddy," from Old French roil "mud, muck, rust" (12c.), from Vulgar Latin *robicula, from Latin robigo "rust" (see robust). An earlier borrowing of the French verb is Middle English roil "to roam or rove about" (early 14c.). Related: Roiled; roiling.
roister (v.): "bluster, swagger, be bold, noisy, vaunting, or turbulent," 1580s, from an obsolete noun roister "noisy bully" (1550s, displaced by 19c. by roisterer), from Middle French ruistre "ruffian," from Old French ruiste "boorish, gross, uncouth," from Latin rusticus (see rustic (adj.)). Related: Roistered; roistering. Ralph Royster-Doyster is the title and lead character of what is sometimes called the first English comedy (Udall, 1555).
Roland: masc. proper name, from French, from Old High German Hrodland, literally "(having a) famous land." As legendary nephew of Charlemagne, celebrated in "Chanson de Roland," c. 1300. His comrade was Oliver, hence a Roland for an Oliver (1610s) in expressions meaning "to give as good as one gets, tit for tat."