retrovirus (n.) Look up retrovirus at Dictionary.com
1977, earlier retravirus (1974), from re(verse) tra(nscriptase) + virus. So called because it contains reverse transcriptase, an enzyme that uses RNA instead of DNA to encode genetic information, which reverses the usual pattern. Remodeled by influence of retro- "backwards."
retune (v.) Look up retune at Dictionary.com
also re-tune, c.1600 of musical instruments; 1974 of engines, from re- + tune (v.). Related: Retuned; retuning.
return (v.) Look up return at Dictionary.com
early 14c., "to come back, come or go back to a former position" (intransitive), from Old French retorner "turn back, turn round, return" (Modern French retourner), from re- "back" (see re-) + torner "to turn" (see turn (v.)). Transitive sense of "report officially" is early 15c.; "to send back" is mid-15c.; that of "to turn back" is from c.1500. Meaning "to give in repayment" is 1590s; that of "give back, restore" c.1600. Related: Returned; returning.
return (n.) Look up return at Dictionary.com
late 14c., "act of coming back," also "official report of election results," from Anglo-French retorn, Old French retorne, verbal noun from retorner (see return (v.)). In ball games from 1833; specifically in tennis from 1886. Meaning "a yield, a profit" is recorded from 1620s. Meaning "a thing sent back" is from 1875. Many happy returns of the day was used by Addison (1716). Mailing return address attested from 1884.
returnable (adj.) Look up returnable at Dictionary.com
early 15c., from return (v.) + -able.
Reuben Look up Reuben at Dictionary.com
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.) Look up reunification at Dictionary.com
1852; see re- + unification.
reunify (v.) Look up reunify at Dictionary.com
also re-unify, 1879, from re- + unify. Related: Reunified; reunifying.
reunion (n.) Look up reunion at Dictionary.com
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.) Look up reunite at Dictionary.com
1590s, from adjective reunit "reunited" (mid-15c.), from Medieval Latin reunitus, past participle of reunire "unite again," from Latin re- "again" (see re-) + unire "join together" (see unite). Related: Reunited; reuniting.
reupholster (v.) Look up reupholster at Dictionary.com
1872, from re- + upholster. Related: Reupholstered; reupholstering.
reuptake (n.) Look up reuptake at Dictionary.com
also re-uptake, by 1977; see re- + uptake (n.).
reusable (adj.) Look up reusable at Dictionary.com
1922, from re- "back, again" + usable. Non-reusable is attested from 1905.
reuse (v.) Look up reuse at Dictionary.com
also re-use, 1843, from re- + use (v.). Related: Reused; reusing.
reuse (n.) Look up reuse at Dictionary.com
1850, from re- + use (n.).
Reuters (n.) Look up Reuters at Dictionary.com
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.) Look up rev at Dictionary.com
1916, from earlier noun (1901), shortening of revolution, in reference to the internal combustion engine. Related: Revved; revving.
revaluate (v.) Look up revaluate at Dictionary.com
1949, back-formation from revaluation.
revaluation (n.) Look up revaluation at Dictionary.com
1610s; see re- + valuation.
revalue (v.) Look up revalue at Dictionary.com
1590s, from re- + value (v.). Related: Revalued; revaluing.
revamp (v.) Look up revamp at Dictionary.com
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.) Look up revanche at Dictionary.com
"revenge," 1858, from French revanche (see revanchist).
revanchist (n.) Look up revanchist at Dictionary.com
"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.) Look up reveal at Dictionary.com
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.) Look up revealed at Dictionary.com
1560s, past participle adjective from reveal. Revealed religion, as opposed to natural religion, is attested from 1719.
revealing (adj.) Look up revealing at Dictionary.com
1590s, past participle adjective from reveal (v.). Related: Revealingly.
reveille (n.) Look up reveille at Dictionary.com
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.) Look up revel at Dictionary.com
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.) Look up revel at Dictionary.com
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.) Look up revelation at Dictionary.com
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.) Look up revelator at Dictionary.com
1801, agent noun from obsolete verb revelate "reveal" (1510s), from Latin revelatus, past participle of revelare (see reveal).
revelatory (adj.) Look up revelatory at Dictionary.com
1882; see revelation + -ory.
reveler (n.) Look up reveler at Dictionary.com
also reveller, late 14c., from Old French revelour, agent noun from reveler (see revel (v.)).
revelry (n.) Look up revelry at Dictionary.com
"act of reveling; merrymaking, boisterous festivity, amusement," early 15c., from revel (n.) + -ery.
revenant (n.) Look up revenant at Dictionary.com
1827, from French revenant (fem. revenante), noun use of present participle of revenir "to return" (see revenue).
revenge (v.) Look up revenge at Dictionary.com
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.) Look up revenge at Dictionary.com
1540s, from Middle French revenge, back-formation from revengier (see revenge (v.)).
revengeful (adj.) Look up revengeful at Dictionary.com
1580s; see revenge (n.) + -ful. Related: Revengefully.
revenue (n.) Look up revenue at Dictionary.com
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.) Look up reverb at Dictionary.com
1961, colloquial shortening of reverberation.
reverberant (adj.) Look up reverberant at Dictionary.com
1570s, from French réverbérant or directly from Latin reverberantem (nominative reverberans), present participle of reverberare (see reverberation).
reverberate (v.) Look up reverberate at Dictionary.com
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.) Look up reverberation at Dictionary.com
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.) Look up revere at Dictionary.com
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.) Look up reverence at Dictionary.com
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.) Look up reverence at Dictionary.com
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.) Look up reverend at Dictionary.com
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.) Look up reverend at Dictionary.com
"clergyman," c.1500, from reverend (adj.).
reverent (adj.) Look up reverent at Dictionary.com
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.) Look up reverential at Dictionary.com
1550s, from Latin reverentia (see reverence) + -al (1). Related: Reverentially.