Online Etymology Dictionary

re-search (v.): "to search again," 1760, from re- + search (v.). Related: Re-searched; re-searching.
re-sign (v.): "sign again," 1805, from re- + sign (v.). Related: Re-signed; re-signing.
re-strain (v.): "strain again," 1874, from re- + strain (v.). Related: Re-strained; re-straining.
re-up (v.): "to re-enlist," 1906, U.S. armed forces slang, from re- "back, again" + up (v.) "enlist." Related: Re-upped; re-upping.
re-view (n.): "a second or repeated viewing," from re- + view (n.).
reach (v.): Old English ræcan, reccan "reach out, stretch out, extend, hold forth," also "succeed in touching, succeed in striking; address, speak to," also "offer, present, give, grant," from West Germanic *raikjan "stretch out the hand" (source also of Old Frisian reka, Middle Dutch reiken, Dutch reiken, Old High German and German reichen), from Proto-Germanic *raikijanau, perhaps from PIE root *reig- "to stretch out" (source also of Sanskrit rjyati "he stretches himself," riag "torture" (by racking); Greek oregein "to reach, extend;" Lithuanian raižius "to stretch oneself;" Old Irish rigim "I stretch").

Shakespeare uses the now-obsolete past tense form raught (Old English ræhte). Meaning "arrive at" is early 14c.; that of "succeed in influencing" is from 1660s. Related: Reached; reaching. Reach-me-down "ready-made" (of clothes) is recorded from 1862, from notion of being on the rack in a finished state.
reach (n.): 1520s, from reach (v.); earliest use is of stretches of water. Meaning "extent of reaching" is from 1540s; that of "act of reaching" is from 1560s.
Ah, but a man's reach should exceed his grasp,
Or what's a heaven for?

[Browning, "Andrea del Sarto"]
react (v.): 1640s, "to exert, as a thing acted upon, an opposite action upon the agent," from re- + act (v.). Chemical sense is from 1944. Related: Reacted; reacting (1610s). For sense development, see reaction. Meaning "perform again" (often re-act) is from 1650s.
reactant: 1901 (n.), 1911 (adj.), from react + -ant.
reaction (n.): "action in resistance or response to another action or power," 1610s, from re- "again, anew" + action (q.v.). Modeled on French réaction, older Italian reattione, from Medieval Latin reactionem (nominative reactio), noun of action formed in Late Latin from past participle stem of Latin reagere "react," from re- "back" + agere "to do, act" (see act (n.)).

Originally scientific; physiological sense is attested from 1805; psychological sense first recorded 1887; general sense of "action or feeling in response" (to a statement, event, etc.) is recorded from 1914. Reaction time, "time elapsing between the action of an external stimulus and the giving of a signal in reply," attested by 1874.
reactionary (adj.): 1831, on model of French réactionnaire (19c.), from réaction (see reaction). In Marxist use, "tending toward reversing existing tendencies," opposed to revolutionary and used opprobriously in reference to opponents of communism, by 1858. As a noun, "person considered reactionary," especially in politics, one who seeks to check or undo political action, by 1855.
reactivate (v.): 1902, from re- "back, again" + activate. Related: Reactivated; reactivating; reactivation.
reactive (adj.): 1712, from react + -ive. Related: Reactively; reactiveness; reactivity.
reactor (n.): "one that reacts," 1835, agent noun in Latin form from react. In nuclear sense, attested from 1945.
read (v.): Old English rædan (West Saxon), redan (Anglian) "to advise, counsel, persuade; discuss, deliberate; rule, guide; arrange, equip; forebode; read, explain; learn by reading; put in order" (related to ræd, red "advice"), from Proto-Germanic *redan (source also of Old Norse raða, Old Frisian reda, Dutch raden, Old High German ratan, German raten "to advise, counsel, guess"), from PIE root *re(i)- "to reason, count" (source also of Sanskrit radh- "to succeed, accomplish," Greek arithmos "number, amount," Old Church Slavonic raditi "to take thought, attend to," Old Irish im-radim "to deliberate, consider"). Words from this root in most modern Germanic languages still mean "counsel, advise."

Sense of "make out the character of (a person)" is attested from 1610s. Connected to riddle (n.1) via notion of "interpret." Transference to "understand the meaning of written symbols" is unique to Old English and (perhaps under English influence) Old Norse raða. Most languages use a word rooted in the idea of "gather up" as their word for "read" (such as French lire, from Latin legere). Read up "study" is from 1842; read out (v.) "expel by proclamation" (Society of Friends) is from 1788. read-only in computer jargon is recorded from 1961.
read (n.): "an act of reading," 1825, from read (v.).
read (adj.): 1580s, "having knowledge gained from reading," in well-read, etc., past participle adjective from read (v.).
read-out (n.): 1946, in computer sense, from read (v.) + out (adv.).
readability (n.): 1829, from readable + -ity.
readable (adj.): 1560s, from read (v.) + -able. Related: Readably.
reader (n.): Old English rædere "person who reads aloud to others; lector; scholar; diviner, interpreter," agent noun from rædan (see read (v.)). Compare Dutch rader "adviser," Old High German ratari "counselor." Old English fem. form was rædistre.
readership (n.): 1719, "office of a reader," from reader + -ship. Meaning "total number of readers of a publication" is from 1914.
readily (adv.): c. 1300, from ready + -ly (2).
readiness (n.): mid-14c., "state of preparation, preparedness;" late 14c., "promptness;" from ready (adj.) + -ness. As "willingness" from c. 1400.
Reading: county town of Berkshire, Old English Readingum (c.900), "(Settlement of) the family or followers of a man called *Read."
reading (n.): Old English ræding, "a reading, the act of reading" either silent or aloud, "a passage or lesson," verbal noun; see read (v.)). Meaning "interpretation" is from mid-14c. (in reference to dreams). Meaning "a form of a passage of text" is from 1550s; that of "a public event featuring reading aloud" is from 1787.
ready (adj.): Old English ræde, geræde "prepared, ready," of a horse, "ready for riding," from Proto-Germanic *garaidijaz "arranged" (source also of Old Frisian rede "ready," Middle Dutch gereit, Old High German reiti, Middle High German bereite, German bereit, Old Norse greiðr "ready, plain," Gothic garaiþs "ordered, arranged"), from PIE root *reidh- "to ride" (see ride (v.)). Lengthened in Middle English by change of ending. Ready-made first attested early 15c.; ready-to-wear is from 1890.
ready (v.): early 13c., "to administer;" c. 1300, "to take aim;" mid-14c., "to prepare, make ready," from ready (adj.). Related: Readied; readying.
Reagan: surname, from Irish riagan, literally "little king." Reaganism first recorded 1966, in reference to policies of Ronald W. Reagan (1911-2004), U.S. governor of California 1967-75, U.S. president 1981-89.
Reaganomics (n.): by Feb. 1981, in reference to economic policies of U.S. President Ronald Reagan, from Reagan + economics.
reagent (n.): 1785, from re- + agent "substance that produces a chemical reaction."
real (adj.): early 14c., "actually existing, true;" mid-15c., "relating to things" (especially property), from Old French reel "real, actual," from Late Latin realis "actual," in Medieval Latin "belonging to the thing itself," from Latin res "matter, thing," of uncertain origin. Meaning "genuine" is recorded from 1550s; sense of "unaffected, no-nonsense" is from 1847.
Generally, by the time you are Real, most of your hair has been loved off, and your eyes drop out and you get loose in the joints and very shabby. But these things don't matter at all, because once you are Real you can't be ugly, except to people who don't understand. [Margery Williams, "The Velveteen Rabbit"]
Real estate, the exact term, is first recorded 1660s, but in Middle English real was used in law in reference to immovable property, paired with, and distinguished from, personal. Noun phrase real time is early 19c. as a term in logic and philosophy, 1953 as an adjectival phrase; get real, usually an interjection, was U.S. college slang in 1960s, reached wide popularity c. 1987.
real (n.): "small Spanish silver coin," 1580s, from Spanish real, noun use of real (adj.) "regal," from Latin regalis "regal" (see regal). Especially in reference to the real de plata, which circulated in the U.S. till c. 1850 and in Mexico until 1897. The same word was used in Middle English in reference to various coins, from Old French real, cognate of the Spanish word.
The old system of reckoning by shillings and pence is continued by retail dealers generally; and will continue, as long as the Spanish coins remain in circulation. [Bartlett, "Dictionary of Americanisms," 1848]
He adds that, due to different exchange rates of metal to paper money in the different states, the Spanish money had varying names from place to place. The Spanish real of one-eighth of a dollar or 12 and a half cents was a ninepence in New England, one shilling in New York, elevenpence or a levy in Pennsylvania, "and in many of the Southern States, a bit." The half-real was in New York a sixpence, in New England a fourpence, in Pennsylvania a fip, in the South a picayune.
realia (n.): "real things," 1952, neuter plural of Late Latin realis "actual, real" (see real (adj.)).
realise (v.): chiefly British English spelling of realize; for suffix, see -ize. Related: Realisation; realised; realising.
realism (n.): 1794, from real (adj.) + -ism; after French réalisme or German Realismus; from Late Latin realis "real." Opposed to idealism in philosophy, art, etc. In reference to scholastic doctrine of Thomas Aquinas (opposed to nominalism) it is recorded from 1826. Meaning "close resemblance to the scene" (in art, literature, etc., often with reference to unpleasant details) is attested from 1856.
realist (n.): c. 1600, in philosophy, from real (adj.) + -ist, and compare French réaliste. Also see realism.
realistic (adj.): "true to reality" (of art, literature, etc.), 1829; "involving a practical view of life" (opposed to idealistic), 1831; from realist + -ic. Related: Realistically.
reality (n.): 1540s, "quality of being real," from French réalité and directly Medieval Latin realitatem (nominative realitas), from Late Latin realis (see real (adj.)). Meaning "real existence, all that is real" is from 1640s; that of "the real state (of something)" is from 1680s. Sometimes 17c.-18c. also meaning "sincerity." Reality-based attested from 1960. Reality television from 1991.
realization (n.): 1610s, "action of making real," from realize + -ation. Meaning "action of forming a clear concept" is from 1828. Related: Realizational.
realize (v.): 1610s, "bring into existence," from French réaliser "make real" (16c.), from Middle French real "actual" (see real (adj.)). Sense of "understand clearly, make real in the mind" is first recorded 1775. Sense of "obtain, amass" is from 1753. Related: Realized; realizing.
really (adv.): c. 1400, originally in reference to the presence of Christ in the Eucharist, from real (adj.) + -ly (2). Sense of "actually" is from early 15c. Purely emphatic use dates from c. 1600; interrogative use (oh, really?) is first recorded 1815.
realm (n.): late 13c., "kingdom," from Old French reaume, probably from roiaume "kingdom," altered (by influence of Latin regalis "regal") from Gallo-Roman *regiminem, accusative form of Latin regimen "system of government, rule" (see regimen). Transferred sense "sphere of activity" is from late 14c.
realpolitik (n.): 1914, from German Realpolitik, which can be translated as "practical politics." See real (adj.) + politics.
Realtor (n.): 1916, "real estate agent," American English, coined by real estate agent Charles N. Chadbourn of Minneapolis, Minn., to distinguish the legitimate section of the business; popularized 1920s; patented as Realtor by the National Association of Real Estate Boards.
The 1916 Convention of the National Association of Real Estate Boards (NAREB) approved the adoption of the term as the official designation of an active member of the Association. In 1920 the District Court of Hennepin County, Minnesota, decided in favor of the Realtors in a case against a telephone directory publisher that had indiscriminately used the word in listings. The court asserted that the word "had never been used in any way whatsoever until so invented" and could thus be used only by those duly licensed by the National Association of Real Estate Boards. Until the Lanham Acts of 1948 changed federal patent regulations to allow protection for registered collective marks, the National Association fought and won sixteen cases on the local and state levels to protect its symbolic property. [Jeffrey M. Hornstein, "The Rise of Realtor," in "The Middling Sorts: Explorations in the History of the American Middle Class," New York, 2001]
realty (n.): 1660s, "real estate," from earlier meaning (1540s) "real possession," earlier "reality" (mid-15c.), from real (adj.) + -ty (2). Compare reality.
ream (n.1): measure of paper, 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 (compare Dutch riem), probably borrowed from Spanish during the time of Hapsburg control of Holland. For ordinary writing paper, 20 quires of 24 sheets each, or 480 sheets; often 500 or more to allow for waste; slightly different numbers for drawing or printing paper.
ream (v.): "to enlarge a hole," 1815, probably a southwest England dialectal survival from Middle English reme "to make room, open up," from Old English ryman "widen, extend, enlarge," from Proto-Germanic *rumijan (source also of Old Saxon rumian, Old Norse ryma, Old Frisian rema, Old High German rumen "to make room, widen"), from *rumaz "spacious" (see room (n.)). Slang meaning "to cheat, swindle" first recorded 1914; anal sex sense is from 1942. To ream (someone) out "scold, reprimand" is recorded from 1950.
ream (n.2): "cream" (obsolete), Old English ream, from Proto-Germanic *raumoz (source also of Middle Dutch and Dutch room, German Rahm), of uncertain origin.
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.