英语词源字典 - 在线词源网站

Ronald [Ronald 词源字典]: masc. proper name, from Old Norse Rögnvaldr "Having the Gods' Power," from rögn "gods," literally "decreeing powers" (plural of regin "decree") + valdr "ruler" (see wield).[Ronald etymology, Ronald origin, 英语词源]
rondeau (n.): 1520s, from Middle French rondeau, from Old French rondel "short poem" (see rondel). Metrical form of 10 or 13 lines with only two rhymes.
rondel (n.): late 14c. as a type of verse, from Old French rondel "short poem," literally "small circle" (13c.), diminutive of roont (fem. roonde) "circular" (see round (adj.)). 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, which is repeated at least once," from Italian rondo, from French rondeau, rondel, from Old French rondel "little round" (see rondel).
ronin (n.): "masterless man, outcast, outlaw," 1871, from Japanese, from ro "wave" + nin "man."
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; "crucifix," especially a large one; also a measure of land, properly 40 square poles or perches, from Proto-Germanic *rod- (cognates: Old Saxon ruoda "stake, pile, cross," Old Frisian rode, Middle Dutch roede, Old High German ruota, German Rute "rod"), from PIE *ret- "post" (cognates: Latin ratis "raft," retae "trees standing on the bank of a stream;" Old Church Slavonic ratiste "spear, staff;" Lithuanian rekles "scaffolding"). Probably not connected with rod.
roof (n.): Old English hrof "roof, ceiling, top, summit; heaven, sky," also figuratively, "highest point of something," from Proto-Germanic *khrofam (cognates: Old Frisian rhoof "roof," Middle Dutch roof, rouf "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.): early 15c., from roof (n.). Related: Roofed; roofing.
roof-top (n.): also rooftop, 1610s, from roof (n.) + top (n.1).
roofer (n.): "one who makes or repairs roofs," 1835, agent noun from roof (v.).
rooibos (n.): 1911, from Afrikaans rooibos, literally "red bush," from rooi "red," from Dutch roi (see red (adj.1)) + bos "bush" (see bush (n.1)).
rook (n.1): "European crow," Old English hroc, from Proto-Germanic *khrokaz (cognates: Old Norse hrokr, Middle Dutch roec, Dutch roek, Middle Swedish roka, Old High German hruoh "crow"), possibly imitative of its raucous voice (compare Gaelic roc "croak," Sanskrit kruc "to cry out"). 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.
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.
rook (v.): "to defraud by cheating" (originally especially in a game), 1590s, from rook (n.1) in some sense (such as "a gull, simpleton," but this is not attested until 17c.). Related: Rooked; rooking.
rookery (n.): "colony of rooks," 1725, from rook (n.1) + -ery.
rookie (n.): "raw recruit," 1892 in that spelling, popularized by Kipling's "Barrack-Room Ballads," of uncertain origin, perhaps from recruit, influenced by rook (n.1) in its secondary sense, suggesting "easy to cheat." Barrère ["A Dictionary of Slang, Jargon & Cant," 1890] has "Rookey (army), a recruit; from the black coat some of them wear," so perhaps directly from rook (n.1). Came into general use in American English during the Spanish-American War.
The rapid growth of a word from a single seed transplanted in a congenial soil is one of the curiosities of literature. Take a single instance. A few weeks ago there was not one American soldier in a thousand who knew there was such a word as "rookey." To-day there are few soldiers and ex-soldiers who have not substituted it for "raw recruit." ["The Midland Monthly," December 1898]
room (n.): Old English rum "space" (extent or time); "scope, opportunity," from Proto-Germanic *ruman (cognates: 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," from PIE root *reue- (1) "to open; space" (cognates: Avestan ravah- "space," Latin rus "open country," Old Irish roi, roe "plain field," Old Church Slavonic ravinu "level," Russian ravnina "a plain"). Old English also had a frequent adjective rum "roomy, wide, long, spacious."

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. Rooming-house is from 1889. In Old English (rumian) and Middle English the verb meant "become clear of obstacles; make clear of, evict."
roomer (n.): "one who hires a room," 1871, agent noun from room (v.).