Online Etymology Dictionary

Romansh: "Rhaeto-Romanic," Latin-derived language spoken in the Grisons region of eastern Switzerland, 1660s, from Grisons Rumansch, from Late Latin Romanice "in Vulgar Latin" (see romance).
romantic (n.): "an adherent of romantic virtues in literature," 1827, from romantic (adj.).
romantic (adj.): 1650s, "of the nature of a literary romance," from French romantique, from Middle French romant "a romance," oblique case of Old French romanz "verse narrative" (see romance). As a literary style, opposed to classical since before 1812. Meaning "characteristic of an ideal love affair" (such as usually formed the subject of literary romances) is from 1660s.
romanticism (n.): 1803, "a romantic idea," from romantic + -ism. Generalized sense of "a tendency toward romantic ideas" is first recorded 1840.
romanticist (n.): 1821; see romantic + -ist.
romanticize (v.): 1818, from romantic + -ize. Related: Romanticized; romanticizing.
Romany (n.): "a gypsy, the Gypsy language," 1812, romani, fem. of romano (adj.) "Gypsy," from rom, the Romany word for "man, husband, male, Gypsy" (plural roma), from Sanskrit domba-s "male member of a low caste of musicians."
Rome: Old English, from Old French Rome, from Latin Roma, of uncertain origin. "The original Roma quadrata was the fortified enclosure on the Palatine hill," according to Tucker, who finds "no probability" in derivation from *sreu- "flow," and suggests the name is "most probably" from *urobsma (cf. urbs, robur) and otherwise, "but less likely" from *urosma "hill" (cf. Sanskrit varsman- "height, point," Lithuanian virsus "upper").

Another suggestion is that it is from Etruscan (cf. Rumon, former name of Tiber River). Common in proverbs, e.g. Rome was not buylt in one daye (1540s), for when a man doth to Rome come, he must do as there is done (1590s), All roads alike conduct to Rome (1806).
Romeo: "a lover, passionate admirer, seducer of women," 1766, from the name of the hero in Shakespeare's tragedy "Romeo and Juliet."
romp (v.): 1709, perhaps a variant of ramp (v.); see rampage. Meaning "to win (a contest) with great ease" first attested 1888. Related: Romped; romping.
romper (n.): 1842, agent noun from romp (v.). Rompers "small children's overalls" first recorded 1909.
Ronald: masc. proper name, from Old Norse Rögnvaldr "Having the Gods' Power," from rögn "gods," literally "decreeing powers" (plural of regin "decree") + valdr "ruler."
rondeau (n.): 1520s, from Middle French rondeau, from Old French rondel (see rondel). Metrical form of 10 or 13 lines with only two rhymes.
rondel (n.): late 14c., from Old French rondel "short poem," literally "small circle," diminutive of roont (fem. roonde) "circular" (see round). Metrical form of 14 lines with only two rhymes. So called because the initial couplet is repeated at the end.
rondo (n.): 1797, "musical composition of one principal theme," from Italian rondo, from French rondeau, rondel, from Old French rondel "little round" (see rondel).
ronin: 1871, from Japanese.
roo (n.): Australian colloquial shortening of kangaroo, attested from 1904.
rood (n.): Old English rod "pole," varying from 6 to 8 yards, also "cross," especially that upon which Christ suffered, also "measure of land," prop. 40 square poles or perches, from Proto-Germanic *rodo (cf. Old Saxon ruoda "stake, pile, cross," Old Frisian rode, Middle Dutch roede, Old High German ruota, German Rute "rod"), probably connected with the root of rod. Klein suggests a connection between this group and Latin ratis "raft," retae "trees standing on the bank of a stream;" Old Church Slavonic ratiste "spear, staff," Lithuanian rekles "scaffolding."
roof (n.): Old English hrof "roof, ceiling, top," from Proto-Germanic *khrofaz (cf. Old Frisian rhoof "roof," Middle Dutch roof "cover, roof," Dutch roef "deckhouse, cabin, coffin-lid," Middle High German rof "penthouse," Old Norse hrof "boat shed").

No apparent connections outside Germanic. "English alone has retained the word in a general sense, for which the other languages use forms corresponding to OE. þæc thatch" [OED]. Roof of the mouth is from late Old English. Raise the roof "create an uproar" is attested from 1860, originally in U.S. Southern dialect.
roof (v.): late 15c., from roof (n.). Related: Roofed; roofing.
roofer (n.): "one who makes or repairs roofs," 1835, agent noun from roof (v.).
rooftop: 1610s; see roof (n.) + top (n.1).
rook (n.1): "European crow," Old English hroc, from Proto-Germanic *khrokaz (cf. Old Norse hrokr, Middle Dutch roec, Middle Swedish roka, Old High German hruoh), possibly imitative of its raucous voice. Used as a disparaging term for persons since at least c.1500, and extended by 1570s to mean "a cheat," especially at cards or dice. The verb "to defraud by cheating" (originally especially in a game) is first attested 1580s.
rook (n.2): "chess piece," c.1300, from Old French roc, from Arabic rukhkh, from Persian rukh, of unknown meaning, perhaps somehow related to the Indian name for the piece, rut, from Hindi rath "chariot." Confused in Middle English with roc.
rookery (n.): "colony of rooks," 1725, from rook (n.1) + -ery.
rookie (n.): 1892, "raw recruit," originally in Kipling's "Barrack-Room Ballads," perhaps from recruit, influenced by rook (n.1) in its secondary sense, suggesting "easy to cheat."
room (n.): Old English rum "space," from Proto-Germanic *ruman (cf. Old Norse, Old Saxon, Old High German, Gothic rum, German Raum "space," Dutch ruim "hold of a ship, nave"), nouns formed from Germanic adjective *ruma- "roomy, spacious," perhaps from a PIE root *rew- "wide, open" (cf. Avestan ravah- "space," Latin rus "open country," Old Irish roi, roe "plain field").

Original sense preserved in make room "clear space for oneself" (late 14c.); meaning "chamber, cabin" first recorded early 14c. as a nautical term, and first applied mid-15c. to chambers within houses. The Old English word for this was cofa, ancestor of cove. Room-service is attested from 1913; room-temperature from 1879. Roomth "sufficient space" (1530s) now is obsolete.
room (v.): "to occupy rooms" (especially with another) as a lodger," 1828, from room (n.). Related: Roomed; rooming.
roommate (n.): 1789, American English, from room (n.) + mate (n.). Short form roomie is from 1918.
roomy (adj.): 1620s, from room (n.) + -y (2). Related: Roominess.
roose (v.): c.1200, â€œto boast;â€ c.1300, â€œto praise,â€ Scottish dialect, from Old Norse hrosa â€œto boast of, to praise.â€
Roosevelt: the family in America originally bore the name Van Roosevelt, "of the field of roses," descriptive of their estates in Holland. Claes Martenszen Van Rosenvelt, born August 1649, emigrated to New Amsterdam. His son (1653) and all his descendants dropped the "Van."
roost (n.): late Old English hrost "wooden framework of a roof, perch," from a Germanic source, related to Old Saxon hrost, Middle Dutch, Flemish, Dutch roest, roost "framework of a roof," Old Norse hrot, Gothic hrot "roof." Exact relationship and ulterior connections unknown. To rule the roost is recorded from 1769.
roost (v.): 1520s, from roost (n.). Related: Roosted; roosting. Chickens come home to roost in reference to eventual consequences of bad actions attested from 1824; the original proverb seems to have been curses, like chickens, come home to roost.
rooster (n.): 1772, agent noun from roost (earlier roost cock, c.1600), in sense of "the roosting bird," favored in the U.S. originally as a puritan alternative to cock (and compare roach).
root (n.): "underground part of a plant," late Old English rot, from Old Norse rot "root," from Proto-Germanic *wrot, *vrot (with characteristic loss of -w- before -r-), from PIE *wrd-. The Old English cognate was wyrt "root, herb, plant" (see wort); also cognate with Latin radix. The usual Old English words for "root" were wyrttruma and wyrtwala.

Figurative use is from c.1200. Of teeth, hair, etc., from early 13c. Mathematical sense is from 1550s. Slang meaning "penis" is recorded from 1846. Root beer first recorded 1841, American English; root doctor is from 1821. Root cap is from 1875.
root (v1.): "dig with the snout," 1530s, from Middle English wroten "dig with the snout," from Old English wrotan, from Proto-Germanic *wrotanan (cf. Old Norse rota, Swedish rota "to dig out, root," Middle Low German wroten, Middle Dutch wroeten, Old High German ruozian "to plow up"), cognate with Latin rodere "to gnaw" (see rodent).

Associated with the verb sense of root (n.). Extended sense of "poke about, pry" first recorded 1831. Phrase root hog or die "work or fail" first attested 1834, American English (in works of Davey Crockett, who noted it as an "old saying"). Reduplicated form rootin' tootin' "noisy, rambunctious" is recorded from 1875.
root (v2.): "cheer, support," 1889, American English, originally in a baseball context, probably from root (v.1) via intermediate sense of "study, work hard" (1856). Related: Rooted; rooting.
root (v.3): "fixed or firmly attached by roots" (often figurative), late 14c., from root (n.); sense of "to pull up by the root" (now usually uproot) also is from late 14c. Related: Rooted; rooting.
rope (n.): Old English rap, from Proto-Germanic *raipaz (cf. Old Norse reip, Middle Dutch, Dutch reep "rope," Gothic skauda-raip "shoe-lace," Old High German, German reif "ring, hoop"). Technically, only cordage above one inch in circumference and below 10 (bigger-around than that is a cable). Nautical use varies. Finnish raippa "hoop, rope, twig" is a Germanic loan-word.

To know the ropes (1840, Dana) is originally a seaman's term. Phrase on the ropes "defeated" is attested from 1924, a figurative extension from boxing. To be at the end of (one's) rope "out of resources and options" is first attested 1680s. Formerly also in many slang and extended uses related to hanging, e.g. John Roper's window "a noose," rope-ripe "deserving to be hanged," both 16c.
rope (v.): c.1300, from rope (n.). Related: Roped; roping.
roque: 1899, "arbitrary alteration of croquet" [OED].
Roquefort: type of cheese, 1837, from the village in the southwest of France, where it originally was made. Reference to salad dressing made from this kind of cheese is from 1943.
Rorschach: 1927, in reference to Swiss psychiatrist Hermann Rorschach (1885-1922), who developed the personality test using ink blots. The town so named on the Swiss side of Lake Constance is from an early form of German Röhr "reeds" + Schachen "lakeside."
Rosa: fem. proper name, from Latin Rosa, literally "rose" (see rose (n.)).
rosacea (n.): short for acne rosacea (1833), from fem. of Latin rosaceus "rose-colored" (see rose).
rosary (n.): mid-15c., "rose garden," from Latin rosarium "rose garden," from neuter of rosarius "of roses," from rosa "rose" (see rose). The sense of "series of prayers" is 1540s, from Middle French rosaire, a figurative use of the word meaning "rose garden," on the notion of a "garden" of prayers. This embodies the medieval conceit of comparing collections to bouquets (cf. anthology and Medieval Latin hortulus animae "prayerbook," literally "little garden of the soul"). Sense transferred 1590s to the strings of beads used as a memory aid in reciting the rosary.
rosÃƒÂ©: light red wine, 1897, from French vin rosé, literally "pink wine."
roscoe (n.): "revolver," 1914, criminals' slang, from the proper name, for some reason.
rose (n.): Old English rose, from Latin rosa (source of Italian and Spanish rosa, French rose; also source of Dutch roos, German Rose, Swedish ros, etc.), probably via Italian and Greek dialects from Greek rhodon "rose" (Aeolic wrodon), ultimately from Persian *vrda-.

But cf. Tucker: "The rose was a special growth of Macedonia & the Thracian region as well as of Persia, & the Lat. & Gk. names prob. came from a Thraco-Phrygian source." Aramaic warda is from Old Persian; the modern Persian cognate, via the usual sound changes, is gul, source of Turkish gül "rose." The ultimate source of all this may be PIE *wrdho- "thorn, bramble."

Used of a color since 1530. In English civil wars of 15c., the white rose was the badge of the House of York, the red of its rival Lancaster. Rose-water is attested from late 14c. Rose-colored "optimistic" is first recorded 1854. In the figurative sense, bed of roses is from 1590s. Rose of Sharon (Song of Sol. ii:1) is attested from 1610s and named for the fertile strip of coastal Palestine. The flower has not been identified; used in U.S. since 1847 of the Syrian hibiscus.