Online Etymology Dictionary

rhapsodic (adj.): 1782, from Greek rhapsodikos "of or for a rhapsodist," from rhapsoidia (see rhapsody). Related: Rhapsodically (c. 1600).
rhapsodist (n.): 1650s, from French rhapsodiste, from rhapsode, from Greek rhapsodos (see rhapsody).
rhapsodize (v.): c. 1600, "to piece together;" 1806, "to talk rhapsodically;" see rhapsody + -ize. Related: Rhapsodized; rhapsodizing.
rhapsodomancy (n.): "divination by means of verses," 1727, from French rhapsodomancie, from Greek rhapsodos "a rhapsodist" (see rhapsody) + -manteia (see -mancy).
There were various methods of practicing this rhapsodomancy. Sometimes they wrote several verses or sentences of a poet on so many pieces of wood, paper, or the like; shook them together in an urn; and drew out one, which was accounted the lot. Sometimes they cast dice on a table, on which verses were written; and that on which the die lodged, contained the prediction. [Rees' "Cyclopedia," London, 1819]
rhapsody (n.): 1540s, "epic poem," from Middle French rhapsodie, from Latin rhapsodia, from Greek rhapsoidia "verse composition, recitation of epic poetry; a book, a lay, a canto," from rhapsodos "reciter of epic poems," literally "one who stitches or strings songs together," from rhaptein "to stitch, sew, weave" (see wrap (v.)) + oide "song" (see ode). Meaning "exalted enthusiastic feeling or expression" is from 1630s. Meaning "sprightly musical composition" is first recorded 1850s.
rhea (n.): South American ostrich, 1801, Modern Latin genus name, for unknown reasons from Greek Rhea, name of a titaness, mother of Zeus, a name of unknown origin. As a moon of Saturn, discovered 1672.
Rhemish (adj.): "of or pertaining to Rheims (earlier English Rhemes), city in northeastern France (see Reims), 1580s; specifically in reference to an English translation of the New Testament by Roman Catholics at the English college there, published 1582.
Rhenish: "of or belonging to the Rhine" (especially of wine), late 14c., from Anglo-French reneis (13c.), from Medieval Latin Rhenensis, from Rhenus (see Rhine).
rhenium (n.): 1925, Modern Latin, from Latin Rhenus "the river Rhine" (see Rhine) + element ending -ium. Coined by German chemists Walter Noddack and Ida Tacke.
rheo-: word-forming element meaning "current of a stream," from Greek rheos "a flowing, stream, current," from PIE root *sreu-; see rheum.
rheology (n.): 1929, from French rhéologie; see rheo- + -logy. Related: Rheologist; rheological.
rheostat (n.): 1843, coined by English physicist Sir Charles Wheatstone (1802-1875) from Greek rheos "a flowing, stream" (from PIE root *sreu-, see rheum) + -stat "regulating device." Related: Rheostatic.
rhesus: 1827, from Modern Latin genus name of a type of East Indian monkey (1799), given by French naturalist Jean-Baptiste Audebert (1759-1800), said to be an arbitrary use of Latin Rhesus, name of a legendary prince of Thrace, from Greek Rhesos.
rhetoric (n.): early 14c., from Old French rethorique, from Latin rhetorice, from Greek rhetorike techne "art of an orator," from rhetor (genitive rhetoros) "speaker, orator, teacher of rhetoric," related to rhesis "speech," rhema "word, phrase, verb," literally "that which is spoken," from PIE *wre-tor-, from root *were- (3) "to speak" (source also of Old English word, Latin verbum, Greek eirein "to say;" see verb).
rhetorical (adj.): mid-15c., "eloquent," from Latin rhetoricus, from Greek rhetorikos "oratorical, rhetorical; skilled in speaking," from rhetor "orator" (see rhetoric). Meaning "pertaining to rhetoric" is from 1520s. Rhetorical question is from 1670s. Related: Rhetorically.
rhetorician (n.): early 15c., Old French rethoricien, from rethorique (see rhetoric). An Old English word for one was wordsawere "word-sower."
rheum (n.): "mucous discharge," late 14c., from Old French reume "a cold" (13c., Modern French rhume), from Latin rheuma, from Greek rheuma "discharge from the body, flux; a stream, current, flood, a flowing," literally "that which flows," from rhein "to flow," from PIE root *sreu- "to flow" (source also of Sanskrit sravati "flows," srotah "stream;" Avestan thraotah- "stream, river," Old Persian rauta "river;" Greek rheos "a flowing, stream," rhythmos "rhythm," rhytos "fluid, liquid;" Old Irish sruaim, Irish sruth "stream, river;" Welsh ffrwd "stream;" Old Norse straumr, Old English stream, Old High German strom (second element in maelstrom); Lettish strauma "stream, river;" Lithuanian sraveti "to trickle, ooze;" Old Church Slavonic struja "river," o-strovu "island," literally "that which is surrounded by a river;" Polish strumień "brook").
rheumatic (adj.): late 14c., from Old French reumatique (Modern French rhumatique), from Latin rheumaticus "troubled with rheum," from Greek rheumatikos, from rheuma "discharge from the body" (see rheum).
rheumatism (n.): c. 1600, from Late Latin rheumatismus, from Greek rheumatismos, from rheumatizein "suffer from the flux," from rheuma "a discharge from the body" (see rheum). "The meaning of a disease of the joints is first recorded in 1688, because rheumatism was thought to be caused by an excessive flow of rheum into a joint thereby stretching ligaments" [Barnhart].
rheumatoid (adj.): 1847, from Greek rheumat-, stem of rheuma "a discharge from the body" (see rheum) + -oid.
rheumatology (n.): 1949, from Greek rheumat-, stem of rheuma "discharge" (see rheum) + -ology. Related: Rheumatologist.
rheumy (adj.): 1590s, from rheum + -y (2).
rhinal (adj.): "pertaining to the nose," 1857, from rhino- + -al (1). Related: Rhinally.
Rhine: principal river in western Germany, from German Rhein, from Middle High German Rin, ultimately from Gaulish Renos, literally "that which flows," from PIE root *reie- "to move, flow, run" (source also of Sanskrit rinati "causes to flow," ritih "stream, course;" Latin rivus "stream;" Old Church Slavonic reka "river;" Middle Irish rian "river, way;" Gothic rinnan "run, flow," rinno "brook;" Middle Low German ride "brook;" Old English riþ "stream;" Old English rinnan, Old Norse rinna "to run," Dutch ril "running stream"). The spelling with -h- (also in Latin Rhenus; French Rhin) is from influence of the Greek form of the name, Rhenos.
Rhineland: 1670s, from German Rheinland; see Rhine + land (n.). Related: Rheinlander.
rhinestone (n.): colorless imitation stone of paste or leaded glass, 1879, a loan-translation of French caillou du Rhin "Rhine pebble," so called because they were made near Strasburg, on the River Rhine, and invented there late 17c. Extensively worn later 18c.
Rhinestone jewelry, a reproduction of the ornaments of the Louis XV. period, is all the rage in Paris. The Rhinestones are as brilliant as diamonds, and being set in silver, will stand any amount of wear or of cleaning. ["The American Stationer," March 20, 1879]
rhinitis (n.): 1829, medical Latin, from rhino- "nose" + -itis "inflammation."
rhino (n.): short for rhinoceros, 1884. As slang for "cash" (also rino) 1680s, of unknown origin. Hence cant rhinocerial "rich" [Grose, 1788].
rhino-: before vowels rhin-, word-forming element meaning "nose, of the nose," from Greek rhino-, comb. form of rhis "nose," which is of uncertain origin.
rhinoceros (n.): c. 1300, from Latin rhinoceros, from Greek rhinokeros, literally "nose-horned," from rhinos "nose" (a word of unknown origin) + keras (genitive keratos) "horn of an animal," from PIE *ker- (1) "horn, head" (see horn (n.)). Related: Rhinocerotic.
What is the plural of rhinoceros? ... Well, Liddell and Scott seem to authorize 'rhinocerotes,' which is pedantic, but 'rhinoceroses' is not euphonious. [Sir Charles Eliot, "The East Africa Protectorate," 1905]
rhinology (n.): 1838, from rhino- + -logy.
rhinoplasty (n.): 1828, from rhino- "nose" + -plasty. Related: rhinoplastic (1823).
rhinorrhea (n.): 1866, from rhino- "nose" + rhoia "flow" (see rheum).
rhinovirus (n.): 1961, from rhino- + virus.
rhizoid (adj.): "root-like," 1858, from Greek rhiza "root," literal and figurative (see rhizome) + -oid. As a noun from 1875.
rhizome (n.): 1832, from Modern Latin rhizoma, from Greek rhizoma "mass of tree roots," from rhizoun "cause to strike root, root into the ground, plant," from rhiza "root," probably from PIE *wrad- "branch, root" (source also of Latin radix "root," Old Norse rot "root," Old English wyrt "plant, herb;" see radish).
rhizophagous (adj.): 1831, from comb. form of Greek rhiza "root" (see rhizome) + -phagous.
Rhode Island: U.S. state, the region is traditionally said to have been named by Italian explorer Giovanni da Verrazzano when he passed through in 1524, based on an imagined similarity between modern Block Island and the Greek Isle of Rhodes. More likely from Roodt Eylandt, the name Dutch explorer Adriaen Block gave to Block Island c. 1614, literally "red island," so called for the color of its cliffs. Under this theory, the name was altered by 17c. English settlers by influence of the Greek island name (see Rhodes), and then extended to the mainland part of the colony. Block Island later (by 1685) was renamed for the Dutch explorer.
Rhodes: Greek island, one of the Dodecanese, from Greek Rhodos, perhaps from rhodon "rose," or rhoia "pomegranate," but "more likely" [Room] from a pre-Greek name, from Phoenician erod "snake," for the serpents which were said to have anciently infested the island.
Rhodes scholar (n.): holder of any of the scholarships founded at Oxford in 1902 by British financier and imperialist Cecil Rhodes (1853-1902), for whom the former African colony of Rhodesia (later Zimbabwe) also was named. The surname is literally "dweller by a clearing," from Old English rodu "plot of land of one square rod."
rhodium (n.): hard white metallic element, 1804, Modern Latin, coined by its discoverer, English physician William H. Wollaston (1766-1828), and named for the color of solutions containing it, from Greek rhodon "rose" (see rose (n.1)) + metallic element ending -ium.
rhododendron (n.): c. 1600, from French rhododendron and directly from Latin rhododendron, from Greek rhododendron, literally "rose-tree," from rhodon "rose" (see rose (n.1)) + dendron "tree" (see dendro-).
rhomb (n.): 1570s, from Middle French rhombe, from Latin rhombus (see rhombus).
rhomboid (n.): 1560s, from Middle French rhomboide or directly from Late Latin rhomboides, from Greek rhomboeides "rhomboidal; a rhomboid;" see rhombus + -oid. Related: Rhomboidal. As an adjective from 1690s.
rhombus (n.): 1560s, from Late Latin rhombus, from Greek rhombos "rhombus, rhomb, lozenge; spinning top, maghic wheel used by sorcerers; a spinning motion," from rhembesthai "to spin, whirl," from PIE *wrembh-, from *werbh- "to turn, twist, bend" (source also of Old English weorpan "to throw away"), from root *wer- (3) "to turn, bend" (see versus).
rhonchus (n.): plural rhonchi, 1829, from Latinized form of Greek rhenkhos, rhankos, properly "a snoring, snorting," from rhenkein "to snore, snort," of imitative origin. Related: Rhonchal; rhonchial.
Rhone: river in southeastern France, from a pre-Indo-European element *rod- meaning "to flow."
rhotacism (n.): 1830, from Modern Latin rhotacismus, from Greek rhotakizein, from rho "the letter -r-," from Hebrew or Phoenician roth. Excessive or peculiar use of the -r- sound (the "burr"), especially the conversion of another sound (usually -s-) to -r-; as in Aeolian Greek, which at the end of words changed -s- into -r- (hippor for hippos, etc.). Related: Rhotacize.
rhubarb (n.): late 14c., from Old French rubarbe, from Medieval Latin rheubarbarum, from Greek rha barbaron "foreign rhubarb," from rha "rhubarb," perhaps ultimately from a source akin to Persian rewend "rhubarb" (associated in Greek with Rha, ancient Scythian name of the River Volga) + barbaron, neuter of barbaros "foreign" (see barbarian). Grown in China and Tibet, it was imported into ancient Europe by way of Russia.

Spelling altered in Medieval Latin by association with rheum. European native species so called from 1640s. Baseball slang meaning "loud squabble on the field" is from 1938, of unknown origin, said to have been first used by broadcaster Garry Schumacher. Perhaps connected with use of rhubarb as a word repeated by stage actors to give the impression of hubbub or conversation (attested from 1934).
rhyme (n.): "agreement in terminal sounds," 1560s, partially restored spelling, from Middle English ryme, rime (c. 1200) "measure, meter, rhythm," later "rhymed verse" (mid-13c.), from Old French rime (fem.), related to Old Provençal rim (masc.), earlier *ritme, from Latin rithmus, from Greek rhythmos "measured motion, time, proportion" (see rhythm).

In Medieval Latin, rithmus was used for accentual, as opposed to quantitative, verse, and accentual verse usually was rhymed, hence the sense shift. Persistence of older form is due to popular association with Old English rim "number," from PIE root *re(i)- "to reason, count" (see read (v.)). Phrase rhyme or reason "good sense" (chiefly used in the negative) is from late 15c. (see reason (n.)). Rhyme scheme is attested from 1931. Rhyme royal (1841) is a stanza of seven 10-syllable lines rhymed a-b-a-b-b-c-c.