Online Etymology Dictionary

realtor (n.): 1916, "real estate agent," American English, coined by C. Chadbourn of Minneapolis, Minn.; patented as Realtor in 1948 by National Association of Real Estate Boards.
realty (n.): 1660s, "real estate," from earlier meaning (1540s) "real possession," earlier "reality" (mid-15c.), from real (adj.) + -ty (2).
ream (n.): mid-14c., from Old French reyme, from Spanish resma, from Arabic rizmah "bundle" (of paper), from rasama "collect into a bundle." The Moors brought manufacture of cotton paper to Spain. Early variant rym (late 15c.) suggests a Dutch influence (cf. Dutch riem), probably during the time of Spanish Hapsburg control of Holland. Properly, 20 quires or 480 sheets, usually 500 or more to allow for waste. Of paper for printing, 21 and a half quires, or 516 sheets (printers' ream).
ream (v.): "to enlarge a hole," 1815, probably a S.W. England dialect survival from Middle English reme "to make room, open up," from Old English ryman "widen, extend, enlarge," from Proto-Germanic *rumijanan (cf. Old Saxon rumian, Old Norse ryma, Old Frisian rema, Old High German rumen "to make room, widen"), from *rumaz "spacious" (see room). Slang meaning "to cheat, swindle" first recorded 1914; anal sex sense is from 1942. To ream (someone) out "scold, reprimand" is recorded from 1950.
reanimate (v.): 1610s, in spiritual and physical sense, from re- "back, again" + animate (v.) "to endow with life." Related: Reanimated; reanimating.
reap (v.): "to cut grain with a hook or sickle," Old English reopan, Mercian form of ripan "to reap," related to Old English ripe "ripe" (see ripe). Related: Reaped; reaping.
reaper (n.): Old English ripere (in compound hripemann), agent noun from reap (v.). As the name of a personification of death, from 1839.
reappear (v.): 1610s, from re- "back, again" + appear. Related: Reappeared; reappearing.
reappearance (n.): 1660s; see reappear + -ance.
reapply (v.): 1723, from re- + apply. Related: Reapplied; reapplying.
reapportionment (n.): 1800, American English, from re- + apportionment.
rear (n.): "hindmost part," c.1600, abstracted from rerewarde "rear guard" (c.1300), from Anglo-French rerewarde, Old French rieregarde, from Old French riere (from Latin retro "back, behind") + Old French garde (see guard). Or the word may be a shortened form of arrear (see arrears).

Military sense of "hindmost part" of an army or fleet is recorded from c.1600. As a euphemism for "buttocks" it is attested from 1796 (rear end in this sense recorded from 1937). Rear admiral is first attested 1580s, apparently so called from ranking "behind" an admiral proper. Rear-view (mirror) is recorded from 1926.
rear (v.): Old English ræran "to raise, build up, set on end," from Proto-Germanic *raizijanau "to raise," causative of *risanan "to rise" (see raise). Meaning "bring into being, bring up" (as a child) is recorded from early 15c.; that of "raise up on the hind legs" is first recorded late 14c. Related: Reared; rearing.
rearm (v.): also re-arm, 1805 (implied in rearming), from re- "back, again" + arm (v.) "to supply with arms." Related: Rearmed; rearming.
rearrange (v.): also re-arrange, 1798, from re- "back, again" + arrange. Related: Rearranged; rearranging; rearrangement.
reason (n.): early 13c., "statement in an argument," also "intellectual faculty that adopts actions to ends," from Anglo-French resoun, Old French raison, from Latin rationem (nominative ratio) "reckoning, understanding, motive, cause," from ratus, past participle of reri "to reckon, think," from PIE root *re(i)- "to reason, count" (cf. Old English rædan "to advise; see read).

Meaning "sanity" is recorded from, late 14c. Phrase it stands to reason is from 1630s. Age of Reason "the Enlightenment" is first recorded 1794, as the title of Tom Paine's book.
reason (v.): c.1400, "to question (someone)," also "to challenge," from Old French raisoner, from Late Latin rationare "to discourse," from ratio (see reason (n.)). Sense of "employ reasoning (with someone)" is from 1847, and that of "to think in a logical manner" is from 1590s. Related: Reasoned; reasoning.
reasonable (adj.): c.1300, "having sound judgment, sane, rational," from Old French raisonable, from Latin rationabilis, from ratio (see reason (n.)).
What the majority of people consider to be 'reasonable' is that about which there is agreement, if not among all, at least among a substantial number of people; 'reasonable' for most people, has nothing to do with reason, but with consensus. [Erich Fromm, "The Heart of Man," 1968]
Meaning "moderate in price" is recorded from 1660s.
reasoning (n.): late 14c., "exercise of the power of reason; act or process of thinking logically; an instance of this;" see reason (v.).
reassemble (v.): late 15c., from re- + assemble. Related: Reassembled; reassembling; reassembler; reassembly.
reassert (v.): 1660s, from re- + assert. Related: Reasserted; reasserting; reassertion.
reassess (v.): 1803; see re- + assess. Related: Reassessed; reassessing.
reassessment (n.): 1777, from re- + assessment.
reassure (v.): "restore (someone) to confidence," 1590s, from re- "back, again" + assure. Related: Reassured; reassuring.
reave (v.): Old English reafian "to rob something from someone, plunder, pillage," from Proto-Germanic *raubjon (cf. Old Frisian ravia, Middle Dutch roven, Dutch rooven, Old High German roubon, German rauben), from PIE *reup- "to snatch" (see rapid (adj.)). Related: Reaved; reaving.
reaver (n.): Old English reafere, agent noun from reafian (see reave).
reb (n.): abbreviation of rebel (n.), 1862, in U.S. Civil War context.
rebar (n.): also re-bar, "steel reinforcing rod in concrete," 1961, from re(inforced) bar.
rebarbative (adj.): 1885, from French rébarbatif (14c.), from barbe "beard."
rebate (v.): early 15c., "to deduct, subtract," from Old French rabattre "beat down, drive back," also "deduct," from re- "repeatedly" (see re-) + abattre "beat down" (see abate). Meaning "to pay back (a sum) as a rebate" is from 1957. Related: Rebated; rebating.
rebate (n.): 1650s, from rebate (v.).
rebbe (n.): 1881, from Yiddish, from Hebrew rabbi (see rabbi).
rebec (n.): "medieval stringed musical instrument," early 15c., from Middle French rebec, an unexplained alteration of Old French ribabe (perhaps somehow influenced by bec "beak"), ultimately from Arabic rebab (cf. Old Provençal rebec, Italian ribeca). It has three strings and is played with a bow.
Rebecca: fem. proper name, biblical wife of Isaac, mother of Jacob and Esau, from Late Latin Rebecca, from Greek Rhebekka, from Hebrew Ribhqeh, literally "connection" (cf. ribhqah "team"), from Semitic base r-b-q "to tie, couple, join" (cf. Arabic rabaqa "he tied fast"). Rebekah, form of the name in Authorized Version, was taken as the name of a society of women (founded 1851 in Indiana, U.S.) as a complement to the Odd Fellows.
rebel (adj.): c.1300, from Old French rebelle (12c.), from Latin rebellis "insurgent, rebellious," from rebellare "to rebel, wage war against," from re- "opposite, against," or perhaps "again" (see re-) + bellare "wage war," from bellum "war."
rebel (v.): late 14c., from Old French rebeller, from Latin rebellare (see rebel (adj.)). Related: Rebelled; rebelling.
rebel (n.): mid-14c., from rebel (adj.). Meaning "supporter of the American cause in the War of Independence" is from 1775; sense of "supporter of the Southern cause in the American Civil War" is attested from April 15, 1861. Rebel yell in an American Civil War context attested from 1862, but the thing itself is older and was said to have been picked up by southwestern men in their periodic wars against the Indians.
The Southern troops, when charging or to express their delight, always yell in a manner peculiar to themselves. ... The Confederate officers declare that the rebel yell has a particular merit, and always produces a salutary and useful effect upon their adversaries. A corps is sometimes spoken of as a 'good yelling regiment.' [A.J.L. Fremantle, "Three Months in the Southern States," 1863]
rebellion (n.): mid-14c., from Old French rebellion (14c.), from Latin rebellionem "renewal of war, revolt," from rebellis (see rebel).
rebellious (adj.): mid-15c., from Latin rebellis (see rebel). Related: Rebelliously; rebelliousness.
rebirth (n.): 1833, from re- + birth (n.).
reboot (v.): 1981, from re- + boot (v.) in the computer sense. Related: Rebooted; rebooting.
rebop (n.): see bebop.
reborn (adj.): 1590s, from re- "back, again" + born.
reborrow (v.): 1630s, from re- "back, again" + borrow. Related: Reborrowed; reborrowing.
rebound (v.): c.1300, "to spring, leap," also "return to afflict" (early 15c.), from Old French rebondir "leap back, resound," from re- "back" (see re-) + bondir "leap, bound" (see bound (v.)). Sense of "to spring back from force of impact" is recorded from late 14c. Sports use probably first in tennis; basketball sense is attested from 1954. Related: Rebounded; rebounding.
rebound (n.): 1520s, from rebound (v.).
rebuff (v.): 1580s, from obsolete French rebuffer "to check, snub," from Italian ribuffare "to check, chide, snide," from ribuffo "a snub," from ri- "back" (from Latin re-, see re-) + buffo "a puff," of imitative origin (cf. buffet (v.)). Related: Rebuffed; rebuffing.
rebuff (n.): 1610s, from rebuff (v.).
rebuild (v.): 1610s, from re- "back, again" + build (v.). Related: Rebuilt; rebuilding.
rebuke (v.): early 14c., "to reprimand, reprove; chide, scold," from Anglo-French rebuker "to repel, beat back," Old French rebuchier, from re- "back" (see re-) + buschier "to strike, chop wood," from busche (French bûche) "wood," from Proto-Germanic *busk- (see bush). Related: Rebuked; rebuking.