Online Etymology Dictionary

reptilian (adj.): 1846, from reptile + -ian. Transferred meaning "malignant, cold, underhanded" is from 1859.
republic (n.): c.1600, "state in which supreme power rests in the people," from French république, from Latin respublica (ablative republica), literally res publica "public interest, the state," from res "affair, matter, thing" + publica, fem. of publicus "public" (see public).
republican (adj.): 1712, "belonging to a republic," from republic + -an (see -ian). In noun sense of "one who favors a republic," it is recorded from 1690s; and in sense of a member of a specific U.S. political party (the Anti-Federalists) from 1782, though this was not the ancestor of the modern U.S. Republican Party, which dates from 1854. Republicrat in U.S. political jargon usually meaning "moderate," is attested from 1940.
republicanism (n.): 1680s, from republican + -ism.
repudiate (v.): 1540s, "to cast off by divorce," from adj. meaning "divorced, rejected, condemned" (mid-15c.), from Latin repudiatus, past participle of repudiare "to divorce or reject," from repudium "divorce, rejection," from re- "back, away" + pudium, probably related to pes-/ped- "foot." The original notion may be of kicking something away, but folk etymology commonly connects it with pudere "cause shame to." Of opinions, conduct, etc., attested from 1824. Related: Repudiated; repudiating.
repudiation (n.): 1540s, "divorce" (of a woman by a man), from Latin repudiationem, noun of action from repudiare (see repudiate). Meaning "action of disowning" is from 1840s.
repudiatory (adj.): 1882; see repudiate + -ory.
repugnance (n.): late 14c., from French répugnance (13c.) or directly from Latin repugnantia, from repugnare (see repugnant).
repugnant (adj.): late 14c., from Latin repugnantem (nominative repugnans), present participle of repugnare "to resist," from re- "back" (see re-) + pugnare "to fight" (see pugnacious).
repulse: 1530s, noun and verb, originally in Bellenden's "Livy," from Latin repulsus, past participle of repellere (see repulsion). Related: Repulsed; repulsing.
repulsion (n.): early 15c., "repudiation," from Late Latin repulsionem, noun of action from repellere (see repel). Meaning "action of forcing or driving back" is attested from 1540s.
repulsive (adj.): 1610s, from French repulsif (14c.), from Medieval Latin repulsivus, from past participle stem of repellere (see repulsion). Originally "able to repel;" the sense of "causing disgust" is first recorded 1816.
repurpose (v.): by 1983, from re- + purpose (v.). Related: Repurposed; repurposing.
reputable (adj.): 1670s; see repute + -able.
reputation (n.): late 14c., from Latin reputationem (nominative reputatio) "consideration," from reputatus, past participle of reputare "reflect upon, reckon," from re- "repeatedly" + putare "to reckon, consider" (see putative).
repute (v.): mid-15c., from French réputer (late 13c.) or directly from Latin reputare Related: Reputed; reputedly. The noun is from 1550s, from the verb.
request (n.): early 14c., from Old French requeste (French requête) "a request," from Vulgar Latin *requæsita, from Latin requisita "a thing asked for," fem. of requisitus "requested, demanded" (see requisite).
request (v.): 1530s, from request (n.). Related: Requested; requesting.
requiem (n.): "mass for repose of the soul of the dead," c.1300, from Latin requiem, accusative singular of requies "rest (after labor), repose," from re-, intensive prefix, + quies "quiet" (see quiet). It is the first word of the Mass for the Dead in the Latin liturgy: "Requiem æternam dona eis, Domine ...."
requiescat: "name of a prayer for the repose of the dead," 1824, from Latin phrase requiescat in pace (often abbreviated R.I.P.), literally "may he begin to rest in peace," from inceptive of requies "rest, repose" (see requiem).
require (v.): c.1300, "to ask a question, inquire," from Old French requerre, from Vulgar Latin *requaerere, from Latin requirere "seek to know, ask," from re- "repeatedly" (see re-) + quaerere "ask, seek" (see query (v.)). The original sense of this word has been taken over by request. Sense of "demand (someone) to do (something)" is from 1751, via the notion of "to ask for imperatively, or as a right" (late 14c.). Related: Required; requiring.
requirement (n.): 1520s, from require + -ment. Related: Requirements.
requisite (adj.): late 15c., from Latin requisitus, past participle of requirere (see require).
requisition (n.): c.1500, from Old French requisition, from Latin requisitionem (nominative requisitio) "a searching," from past participle stem of requisitus (see requisite). As a verb, from 1837. Related: Requisitioned; requisitioning.
requisitioner (n.): 1968, agent noun from requisition. Earlier was requisitionist (1819).
requital (n.): 1570s, from requite + -al (2).
requite (v.): 1520s, from re- "back" + Middle English quite "clear, pay up" (see quit). Related: Requited; requiting.
reread (v.): 1782, from re- + read. As a noun, from 1973.
reredos (n.): late 14c., from Anglo-French rere-, archaic comb. form of rear, + dos "back" (see dossier).
reroute (v.): also re-route, 1929, from re- "back, again" + route (v.). Related: Rerouted; rerouting.
rerun (v.): 1804, in reference to races, from re- "back, again" + run (q.v.). The noun, in reference to filmed television, is recorded from 1934.
res ipsa loquitur: Latin, "the thing speaks for itself."
res judicata: a point decided by authority.
resale (n.): 1620s, from re- "back, again" + sale (q.v.).
reschedule (v.): 1966, from re- "back, again" + schedule (v.). Related: Rescheduled; rescheduling.
rescind (v.): 1630s, from Latin rescindere "to cut off, tear off, abolish," from re- "back" + scindere "to cut, split" (see shed (v.)). Related: Rescinded; rescinding.
rescission (n.): 1650s, from Late Latin rescissionem, noun of action from rescindere (see rescind).
rescue: c.1300 (n. and v.), from stem of Old French rescourre, from re-, intensive prefix, + escourre "to cast off, discharge," from Latin excutere "to shake off, drive away," from ex- "out" + -cutere, combining form of quatere "to shake" (see quash).
research: 1570s, "act of searching closely," from Middle French recerche (1530s), from Old French recercher "seek out, search closely," from re-, intensive prefix, + cercher "to seek for" (see search). Meaning "scientific inquiry" is first attested 1630s. Related: Researched; researching. Phrase research and development is recorded from 1923.
resect (v.): 1650s, from Latin resectus, past participle of resecare "to cut off," from re- + secare "to cut" (see section (n.)). Surgical sense is from 1846. Related: Resected; resecting.
resection (n.): 1610s, from Latin resectionem, noun of action from resecare (see resect).Surgical sense is from 1775.
resemblance (n.): late 14c., from Anglo-French resemblance (c.1300); see resemble + -ance.
resemble (v.): mid-14c., from Old French resembler (12c.), from re-, intensive prefix, + sembler "to appear, to seem, be like," from Latin simulare "to copy." Related: Resembled; resembling.
resend (v.): 1550s, from re- + send. Related: Resent; resending.
resent (v.): c.1600, from French ressentir "feel pain, regret," from Old French resentir (13c.), from re-, intensive prefix, + sentir "to feel," from Latin sentire (see sense (n.)). Related: Resented; resenting.
resentful (adj.): 1650s, from resent + -ful. Related: Resentfully; resentfulness.
resentment (n.): 1610s, from French ressentiment (16c.), from ressentir (see resent).
"Ridicule often parries resentment, but resentment never yet parried ridicule." [Walter Savage Landor, "Imaginary Conversations"]
reservation (n.): late 14c., "act of reserving," from Middle French reservation, from Late Latin reservationem (nominative reservatio), noun of action from past participle stem of Latin reservare (see reserve (n.)). U.S. Indian tribe sense is recorded from 1789, originally in reference to the Six Nations in New York State. Meaning "act or fact of engaging a room, a seat, etc." is from 1904, originally American English.
reserve (v.): mid-14c., from Old French reserver, from Latin reservare "keep back, save back," from re- "back" + servare "to keep, save, preserve, protect" (see observe). Reserved (in manner) first recorded 1601 in Shakespeare ("All's Well" v.3).
reserve (n.): "something stored up," 1650s, from reserve (v.).