Online Etymology Dictionary

rehash (v.): 1822, from re- "again" + hash (v.). The noun is first attested 1849.
rehearse: c.1300, "to give an account of," from Anglo-Fr. rehearser, O.Fr. rehercier "to go over again, repeat," lit. "to rake over," from re- "again" + hercier "to rake, harrow" (see hearse). Meaning "to say over again" is from mid-14c.; sense of "practice a play, part, etc." is from 1570s. Rehearsal dinner first attested 1953.
reheat (v.): 1727, from re- "again" + heat (v.).
Rehoboth: Heb. Rehobhoth, lit. "wide places" (Gen. xxvi.22).
Reichstag: "German imperial parliament" (1871-1918), earlier used of the parliament of the North German Confederacy, 1867, from Ger. Reich "empire, kingdom" (from O.H.G. rihhi, related to O.E. rice, from P.Gmc. *rikja "rule") + Tag "assembly," lit. "day" (see day).
reification: 1846, "act of materializing," from L. re-, stem of res "thing." In Marxist jargon, translating Ger. Verdinglichung.
reign (n.): early 13c., "kingdom," from O.Fr. reigne, from L. regnum "kingship, dominion, rule, realm," related to regere (see regal). Meaning "period of rule" first recorded mid-14c. The verb, meaning "to hold or exercise sovereign power," is attested from late 13c., from O.Fr. regner, from L. regnare, from regnum.
reimburse: 1611, from re- "back" + imburse "to pay, enrich," lit. "put in a purse" (c.1530), from M.Fr. embourser, from O.Fr. em- "in" + borser "to get money," from borse "purse," from M.L. bursa (see purse).
rein (n.): c.1300, "strap fastened to a bridle," from O.Fr. rene, probably from V.L. *retina "a bond, check," back-formation from L. retinere "hold back" (see retain). The verb is c.1300, from the noun. Figurative extension "put a check on" first recorded 1588.
reincarnation: 1858, from re- "back, again" + incarnation (q.v.). The verb reincarnate also is attested from 1858.
reindeer: c.1400, from O.N. hreindyri "reindeer," from dyr "animal" (see deer) + hreinn, the usual name for the animal, from P.Gmc. *khrainaz (cf. O.E. hran "reindeer," Ger. Renn). Probably cognate with Gk. krios "ram," but folk-etymology associates it with rennen "to run."
reinforce: 1600, originally in military sense, from re- "again" + enforce (cf. re-enforce).
reissue (v.): 1618, from re- "back, again" + issue (q.v.). The noun is attested from 1805.
reiterate: 1526, from L. reiteratus, pp. of reiterare "to repeat," from re- "again" + iterare "to repeat," from iterum "again."
reject: c.1415, from L. rejectus, pp. of reicere "to throw back," from re- "back" + -icere, comb. form of jacere "to throw" (see jet (v.)). The noun is first recorded 1555; rare before 20c. Rejection in the psychological sense, relating to parenting, is recorded from 1931.
rejoice: c.1300, "to enjoy the possession of," from O.Fr. rejoiss-, stem of rejoissant, prp. of rejoir "gladden, rejoice," from re-, intensive prefix + joir "be glad," from L. gaudere "rejoice" (see joy). Originally sense in to rejoice in. Meaning "to be full of joy" is recorded from late 14c.
rejoin (1): "join again," 1540s, from re- "again" + join.
rejoin (2): "to answer," mid-15c., legal term, from M.Fr. rejoin-, stem of rejoindre "to answer to a legal charge," from O.Fr. re- "back" + joindre "to join" (see join). General (non-legal) meaning first recorded 1630s. Rejoinder is mid-15c., from M.Fr. rejoindre; originally "defendant's answer to the replication."
rejuvenate: 1807, from re- "again" + L. juvenis (see young). Noun rejuvensecence "renewal of youth" is first recorded 1631.
rekindle: 1593, from re- "back, again" + kindle (q.v.).
relapse (v.): 1568, from L. relapsus, pp. of relabi "slip back," from re- "back" + labi "to slip" (see lapse). The noun is first attested 1533.
relate: 1530, "to recount, tell," from L. relatus, used as pp. of referre (see refer), from re- "back, again" + latus (see oblate (n.)). Meaning "to establish a relation between" is from 1771. Sense of "to feel connected or sympathetic to" is attested from 1950, originally in psychology jargon. Related in the sense of "connected by blood or marriage" is from 1702.
relation: late 14c., from Anglo-Fr. relacioun, O.Fr. relacion (14c.), from L. relationem (nom. relatio) "a bringing back, restoring," from relatus (see relate). Meaning "person related by blood or marriage" first attested c.1500. Stand-alone phrase no relation "not in the same family" is attested by 1930.
relationship: 1744, "sense of being related," from relation + -ship. Specifically of romantic or sexual relationships by 1944.
relative (n.): 1388, "a relative pronoun," from O.Fr. relatif (13c.), from L.L. relativus "having reference or relation," from L. relatus, pp. of referre "to refer." Meaning "person in the same family" first recorded 1657; the adj. is attested from 1530. Relatively "in relation to something else" is recorded from 1561. Relativism in philosophy first recorded 1865 (relativist is from 1863).
relativity: 1834, "fact or condition of being relative," from relative (adj.) (see relative (n.)); first attested in Coleridge. In scientific use, connected to the theory of Albert Einstein (1879-1955), published 1905 (special theory of relativity) and 1915 (general theory of relativity), but the word was used in roughly this sense by J.C. Maxwell in 1876.
relax: c.1420, "to make (something) less compact or dense," from O.Fr. relaxer (14c.), from L. relaxare "relax, loosen, open," from re- "back" + laxare "loosen," from laxus "loose" (see lax). Of persons, attested from 1837, "to become less formal;" meaning "to become less tense" is recorded from 1935. Relaxation "relief from work" first recorded 1548.
relay (n.): c.1410, "hounds placed along a line of chase," from M.Fr. relai "reserve pack of hounds or other animals" (13c.), from O.Fr. relaier "to exchange tired animals for fresh," lit. "leave behind," from re- "back" + laier "to leave" (see delay). The etymological sense is "to leave (dogs) behind (in order to take fresh ones)." Of horses, 1659. Electromagnetic sense first recorded 1860. As a type of foot-race, it is attested from 1898. The verb is first attested c.1410.
release (v.): c.1300, "to withdraw, revoke," also "to liberate" (c.1300), from O.Fr. relaisser "to relinquish, quit, let go, leave behind," variant of relacher "release, relax," from L. relaxare (see relax). Meaning "relinquish, surrender" is recorded from late 14c. Of press reports, attested from 1904; of motion pictures, from 1912; of music recordings, from 1962. As a euphemism for "to dismiss, fire from a job" it is attested in Amer.Eng. since 1904.
release (n.): early 14c., from O.Fr. reles (12c.), a back formation from relesser, relaisser (see release (v.)).
relegate: 1586 "to banish, send into exile" (implied in relegation), from L. relegatus, pp. of relegare "remove, dismiss, banish," from re- "back" + legare "send with a commission" (see legate). Meaning "place in a position of inferiority" is recorded from 1790.
relent: late 14c., "to melt, soften, dissolve," from re-, intensive prefix + L. lentus "slow, viscous, supple" (see lithe). Sense of "become less harsh or cruel" first recorded 1520s. The notion is probably of a hard heart melting with pity.
relentless: 1590s, from relent + -less.
relevant: "pertinent to the matter at hand," 1560, from M.L. relevantem (1481), prp. of L. relevare "to lessen, lighten" (see relieve). Originally a Scottish legal term meaning "take up, take possession of property;" not generally used until after 1800. Relevance is from 1733 (relevancy in the same sense is recorded from 1561).
reliable: 1569, raliabill, Scottish, from rely + -able. Not common before 1850; and execrated thereafter in Britain as an Americanism.
reliance: 1607, from rely (q.v.) + -ance. The adj. reliant is attested from 1856. Since it means "dependent (on)" it would seem an odd name for an automobile, but Chrysler (Plymouth) nonetheless chose it as one in 1981.
relic: early 13c., "body part or other object from a holy person," from O.Fr. relique (11c.), from L.L. reliquiæ (pl.) "remains of a martyr," from L., "remains, remnants," noun use of fem. pl. of reliquus "remaining, that which remains," from re- "back" + root of linquere "to leave" (see relinquish). Sense of "remains, ruins" is from early 14c. Old English used reliquias, directly from Latin.
relict: "widow," c.1460, from M.L. relicta "widow," noun use of fem. of relictus "abandoned, left behind," prop. pp. of L. relinquere "to leave behind" (see relinquish).
relief (1): "ease, alleviation," early 14c., from Anglo-Fr. relif, from O.Fr. relief "assistance," lit. "a raising, that which is lifted," from stressed stem of relever (see relieve). Meaning "aid to impoverished persons" is attested from c.1400; that of "deliverance of a besieged town" is from 1540s.
relief (2): "projection of figure or design from a flat surface," 1606, from It. rilievo, from rilevare "to raise," from L. relevare "to raise, lighten" (see relieve).
relieve: c.1300, from O.Fr. relever "to raise, relieve" (11c.), from L. relevare "to raise, alleviate," from re-, intensive prefix, + levare "to lift up, lighten," from levis "not heavy" (see lever). The notion is "to raise (someone) out of trouble." Reliever in the baseball pitcher sense is recorded from 1967. Related: relieved.
religieuse: "a nun," 1694, from Fr., fem. of religieux "monk," prop. "religious," from O.Fr. religion (see religion). As a type of pastry, attested from 1929.
religion: c.1200, "state of life bound by monastic vows," also "conduct indicating a belief in a divine power," from Anglo-Fr. religiun (11c.), from O.Fr. religion "religious community," from L. religionem (nom. religio) "respect for what is sacred, reverence for the gods," in L.L. "monastic life" (5c.); according to Cicero, derived from relegare "go through again, read again," from re- "again" + legere "read" (see lecture). However, popular etymology among the later ancients (and many modern writers) connects it with religare "to bind fast" (see rely), via notion of "place an obligation on," or "bond between humans and gods." Another possible origin is religiens "careful," opposite of negligens. Meaning "particular system of faith" is recorded from c.1300.
"To hold, therefore, that there is no difference in matters of religion between forms that are unlike each other, and even contrary to each other, most clearly leads in the end to the rejection of all religion in both theory and practice. And this is the same thing as atheism, however it may differ from it in name." [Pope Leo XIII, Immortale Dei, 1885]
Modern sense of "recognition of, obedience to, and worship of a higher, unseen power" is from 1530s. Religious is first recorded early 13c. Transferred sense of "scrupulous, exact" is recorded from 1590s.
relinquish: 1472, from M.Fr. relinquiss-, prp. stem of relinquir (12c.), from L. relinquere "leave behind, forsake, abandon, give up," from re- "back" + linquere "to leave," from PIE *linkw-, from base *leikw- "to leave behind" (cf. Skt. reknas "inheritance, wealth," rinakti "leaves;" Gk. leipein "to leave;" Goth. leihvan, O.E. lænan "to lend;" O.H.G. lihan "to borrow;" O.N. lan "loan").
reliquary: "receptacle for keeping relics," 1656, from Fr. reliquaire (14c.), from O.Fr. relique (see relic).
relique: Frenchified spelling of relic (q.v.).
reliquiae: "remains," 1654, from L., pl. of reliquus "remaining," related to relinquere (perf. reliqui) "to leave behind" (see relinquish).
relish: 1530, "taste, flavor," alteration of reles "scent, taste, aftertaste," (c.1320), from O.Fr. relais, reles "something remaining, that which is left behind," from relaisser (see release). Meaning "enjoyment of the taste or flavor of something" is attested from 1649. Sense of "condiment" is first recorded 1797. The verb is attested from 1567 (implied in relished); sense of "to enjoy, take pleasure in" is from 1594.
relive: 1540s, "to come to life again" (also "to restore to life again"), from re- "back, again" + live (v.). Meaning "to experience over again" is attested from c.1711.
reload (v.): 1778, from re- "back, again" + load (v.).