Online Etymology Dictionary

returnable (adj.): early 15c., from return (v.) + -able.
Reuben: masc. proper name, Old Testament eldest son of Jacob and name of the tribe descended from him, from Greek Rouben, from Hebrew Reubhen, probably literally "Behold a son," from reu, imperative of ra'ah "he saw" + ben "a son." As a typical name of a farmer, rustic, or country bumpkin, from 1804. The reuben sandwich (1956) is "Not obviously connected" with the sense in rube [OED], possibly from Reuben's restaurant, a popular spot in New York's Lower East Side.
reunification (n.): 1852; see re- + unification.
reunify (v.): also re-unify, 1879, from re- + unify. Related: Reunified; reunifying.
reunion (n.): c. 1600, "act or fact of coming together again," from re- "back, again" + union; or from French réunion (1540s). Meaning "meeting of persons of previous connection" is from 1820.

The island of Reunion, formerly known as Bourbon, was renamed during the French Revolution (1793) in commemoration of the 1792 union of revolutionaries from Marseille with the National Guard in Paris, renamed back to Bourbon after 1815, then back to the Revolutionary name after 1848.
reunite (v.): c. 1500, from Medieval Latin reunitus, past participle of reunire "unite again," from Latin re- "again" (see re-) + Late Latin unire "join together, make into one" (see unite). Related: Reunited; reuniting.
reupholster (v.): 1872, from re- + upholster. Related: Reupholstered; reupholstering.
reuptake (n.): also re-uptake, by 1977; see re- + uptake (n.).
reusable (adj.): 1922, from re- "back, again" + usable. Non-reusable is attested from 1905.
reuse (v.): also re-use, 1843, from re- + use (v.). Related: Reused; reusing.
reuse (n.): 1850, from re- + use (n.).
Reuters (n.): news service begun in London 1851 by Baron Paul Julius von Reuter (1816-1899), founder of a telegraph office and pigeon post bureau in Aachen in 1849.
rev (v.): 1916, from earlier noun (1901), shortening of revolution, in reference to the internal combustion engine. Related: Revved; revving.
revaluate (v.): 1949, back-formation from revaluation.
revaluation (n.): 1610s; see re- + valuation.
revalue (v.): 1590s, from re- + value (v.). Related: Revalued; revaluing.
revamp (v.): 1850, from re- "again" + vamp (v.) "patch up, replace the upper front part of a shoe." An earlier verb was new-vamp (1630s). Modern use is typically figurative. Related: Revamped; revamping.
revanche (n.): "revenge," 1858, from French revanche (see revanchist).
revanchist (n.): "a German seeking to avenge Germany's defeat in World War I and recover lost territory," 1926 (on model of French revanchiste, used in reference to those seeking to reverse the results of the defeat of France by Prussia in 1871), from revanche "revenge, requital," especially in reference to a national policy seeking return of lost territory, from French revanche "revenge," from Middle French revenche, back-formation from revenchier (see revenge (v.)). Related: Revanchism (1954).
reveal (v.): late 14c., from Old French reveler "reveal" (14c.), from Latin revelare "reveal, uncover, disclose," literally "unveil," from re- "opposite of" (see re-) + velare "to cover, veil," from velum "a veil" (see veil (n.)). Related: Revealed; revealing.
revealed (adj.): 1560s, past participle adjective from reveal. Revealed religion, as opposed to natural religion, is attested from 1719.
revealing (adj.): 1590s, past participle adjective from reveal (v.). Related: Revealingly.
reveille (n.): 1640s, from French réveillez-vous "awaken!" imperative plural of réveiller "to awaken, to wake up," from Middle French re- "again" (see re-) + eveiller "to rouse," from Vulgar Latin *exvigilare, from Latin ex- "out" + vigilare "be awake, keep watch" (see vigil).
revel (n.): late 14c., "riotous merry-making," from Old French revel "entertainment, revelry," verbal noun from reveler "be disorderly, make merry" (see revel (v.)). Related: Revels; revel-rout.
revel (v.): early 14c., "to feast in a noisy manner;" late 14c., "take part in revels," from Old French reveler, also rebeller "be disorderly, make merry; rebel, be riotous," from Latin rebellare "to rebel" (see rebel (v.)). The meaning "take great pleasure in" first recorded 1754. Related: Reveled; reveling; revelled; revelling.
revelation (n.): c. 1300, "disclosure of information to man by a divine or supernatural agency," from Old French revelacion and directly from Latin revelationem (nominative revelatio), noun of action from past participle stem of revelare "unveil, uncover, lay bare" (see reveal). General meaning "disclosure of facts" is attested from late 14c.; meaning "striking disclosure" is from 1862. As the name of the last book of the New Testament (Revelation of St. John), it is first attested late 14c. (see apocalypse); as simply Revelations, it is first recorded 1690s.
revelator (n.): 1801, agent noun from obsolete verb revelate "reveal" (1510s), from Latin revelatus, past participle of revelare (see reveal).
revelatory (adj.): 1882; see revelation + -ory.
reveler (n.): also reveller, late 14c., from Old French revelour, agent noun from reveler (see revel (v.)).
revelry (n.): "act of reveling; merrymaking, boisterous festivity, amusement," early 15c., from revel (n.) + -ery.
revenant (n.): "one who returns," especially after a long absence; "a ghost," 1814 (in "Rosanne" by Laetitia Matilda Hawkins), from French revenant (fem. revenante), noun use of present participle of revenir "to return" (see revenue).
revenge (v.): late 14c., from Old French revengier, variant of revenchier "take revenge, avenge" (13c., Modern French revancher), from re-, intensive prefix (see re-), + vengier "take revenge," from Latin vindicare "to lay claim to, avenge, punish" (see vindicate).
To avenge is "to get revenge" or "to take vengeance"; it suggests the administration of just punishment for a criminal or immoral act. Revenge seems to stress the idea of retaliation a bit more strongly and implies real hatred as its motivation. ["The Columbia Guide to Standard American English," 1993]
revenge (n.): 1540s, from Middle French revenge, back-formation from revengier (see revenge (v.)).
revengeful (adj.): 1580s; see revenge (n.) + -ful. Related: Revengefully.
revenue (n.): early 15c., "income from property or possessions," from Middle French revenue, in Old French, "a return," noun use of fem. past participle of revenir "come back" (10c.), from Latin revenire "return, come back," from re- "back" (see re-) + venire "come" (see venue). Meaning "public income" is first recorded 1680s; revenue sharing popularized from 1971. Revenuer "U.S. Department of Revenue agent," the bane of Appalachian moonshiners, first attested 1880.
reverb (n.): 1961, colloquial shortening of reverberation.
reverberant (adj.): 1570s, from French réverbérant or directly from Latin reverberantem (nominative reverberans), present participle of reverberare (see reverberation).
reverberate (v.): 1570s, "beat back, drive back, force back," from Latin reverberatus, past participle of reverberare "strike back, repel, cause to rebound" (see reverberation). Meaning "re-echo" is from 1590s. Earlier verb was reverberen (early 15c.). Related: Reverberated; reverberating.
reverberation (n.): late 14c., "reflection of light or heat," from Old French reverberacion "great flash of light; intense quality," from Medieval Latin reverberationem (nominative reverberatio), noun of action from past participle stem of Latin reverberare "beat back, strike back, repel, cause to rebound," from re- "back" (see re-) + verberare "to strike, to beat," from verber "whip, lash, rod," related to verbena "leaves and branches of laurel," from PIE *werb- "to turn, bend" (see warp (v.)). Sense of "an echo" is attested from 1620s.
revere (v.): 1660s, from French révérer, from Latin revereri "revere, fear" (see reverence (n.), which also was the earlier form of the verb). Related: Revered; revering.
reverence (n.): late 13c., from Old French reverence "respect, awe," from Latin reverentia "awe, respect," from revereri "to stand in awe of, respect, honor, fear, be afraid of; revere," from re-, intensive prefix (see re-), + vereri "stand in awe of, fear, respect," from PIE *wer-e-, suffixed form of root *wer- (4) "to be or become aware of, perceive, watch out for" (see ward (n.)).
reverence (v.): late 14c., "treat with respect, honor; venerate, pay pious homage to; esteem, value; bow to (someone); do honor to," from reverence (n.). Related: Reverenced; reverencing.
reverend (adj.): early 15c., "worthy of respect," from Middle French reverend, from Latin reverendus "(he who is) to be respected," gerundive of revereri (see reverence). As a form of address for clergymen, it is attested from late 15c.; earlier reverent (late 14c. in this sense). Abbreviation Rev. is attested from 1721, earlier Revd. (1690s). Very Reverend is used of deans, Right Reverend of bishops, Most Reverend of archbishops.
reverend (n.): "clergyman," c. 1500, from reverend (adj.).
reverent (adj.): late 14c., "reverend;" late 15c., "characterized by reverence, deeply respectful," from Old French reverent and directly from Latin reverentem (nominative reverens), present participle of revereri (see reverence). The sense of "reverend" was common 14c. through 17c. Related: Reverently.
reverential (adj.): 1550s, from Latin reverentia (see reverence) + -al (1). Related: Reverentially.
reverie (n.): mid-14c., reuerye, "wild conduct, frolic," from Old French reverie, resverie "revelry, raving, delirium" (Modern French rêverie), from resver "to dream, wander, rave" (12c., Modern French rêver), of uncertain origin (also the root of rave). Meaning "daydream" is first attested 1650s, a reborrowing from French. As a type of musical composition, it is attested from 1880. Related: Reverist.
reversal (n.): late 15c., from reverse (v.) + -al (2).
reverse (adj.): c. 1300, from Old French revers "reverse, cross, opposite" (13c.), from Latin reversus, past participle of revertere "turn back, turn about, come back, return" (see revert). Reverse angle in film-making is from 1934. Reverse discrimination is attested from 1962, American English.
reverse (n.): mid-14c., "opposite or contrary" (of something), from reverse (adj.) or from Old French Related: revers "the opposite, reverse." Meaning "a defeat, a change of fortune" is from 1520s; meaning "back side of a coin" is from 1620s. Of gear-shifts in motor cars, from 1875. As a type of sports play (originally rugby) it is recorded from 1921.