Rh [,är-'āch] -adj

  1. of, relating to, or being an Rh factor
    • Rh antigens
    • Rh sensitization in pregnancy
  2. rhodium

RH -abbr

  1. relative humidity
  2. right hand; right hander

rhabdo- -comb form

  1. rodlike structure
    • rhabdo virus

rhab·do·coele ['rab-də-,sēl] -n

  1. a turbellarian worm (order Rhabdocoela) with an unbranched intestine

rhab·dom ['rab-,däm, -dəm] -n

  1. one of the minute rodlike structures in the retinulae in the compound eyes of arthropods

rhab·do·man·cy ['rab-də-,man(t)-sē] -n

  1. divination by rods or wands

rhab·do·mere [-,mir] -n

  1. a division of a rhabdom

rhab·do·my·ol·y·sis [,rab-dō-mī-'ä-lə-səs] -n

  1. the destruction or degeneration of muscle tissue (as from traumatic injury, excessive exertion, or stroke) accompanied by the release of breakdown products into the bloodstream and sometimes leading to acute renal failure

rhab·do·myo·sar·co·ma ['rab-(,)dō-,mī-ə-sär-'kō-mə] -n

  1. a malignant tumor composed of striated muscle fibers

rhab·do·vi·rus [-,vī-rəs] -n

  1. any of a family ( Rhabdoviridae) of rod- or bullet-shaped single-stranded RNA viruses found in plants and animals and including the causative agents of rabies and vesicular stomatitis

rhad·a·man·thine [,ra-də-'man(t)-thən, -'man-,thīn] -adj

  1. rigorously strict or just

Rhad·a·man·thus [,ra-də-'man(t)-thəs] -n

  1. a judge of the underworld in Greek mythology

Rhae·toRo·mance [,rē-tō-rō-'man(t)s, -tō-rə-; -'rō-,man(t)s] -n

  1. a group of Romance languages spoken in eastern Switzerland and northeastern Italy

rham·nose ['ram-,nōs, -,nōz] -n

  1. a crystalline sugar C 6H 12O 5that occurs usu. in the form of a glycoside in many plants and is obtained in the common dextrorotatory lform

rhap·sode ['rap-,sōd] -n

  1. rhapsodist

rhap·sod·ic [rap-'sä-dik] -adj, adv

  1. extravagantly emotional : rapturous
  2. resembling or characteristic of a rhapsody

rhap·so·dist ['rap-sə-dist] -n

  1. a professional reciter of epic poems
  2. one who writes or speaks rhapsodically

rhap·so·dize [-sə-,dīz] -vi

  1. to speak or write in a rhapsodic manner
    • rhapsodize about a new book

rhap·so·dy ['rap-sə-dē] -n

  1. a portion of an epic poem adapted for recitation
  2. a miscellaneous collection
  3. a highly emotional utterance
  4. a highly emotional literary work
  5. effusively rapturous or extravagant discourse
  6. rapture, ecstasy
  7. a musical composition of irregular form having an improvisatory character

rhea ['rē-ə] -n

  1. either of two So. American ratite birds ( Rhea americanaand Pterocnemia pennataof the family Rheidae) that resemble but are smaller than the African ostrich and that have three toes, a fully feathered head and neck, an undeveloped tail, and pale gray to brownish feathers that droop over the rump and back

rhe·bok ['rē-,bäk] -n

  1. a brownish-gray antelope ( Pelea capreolus) of southern Africa

rhe·ni·um ['rē-nē-əm] -n

  1. a rare heavy metallic element that is obtained either as a gray powder or as a silver-white hard metal, is usu. extracted as a by-product of molybdenum smelting, and is used esp. in catalysts and alloys

rheo- -comb form

  1. flow : current
    • rheo stat

rhe·ol·o·gy [rē-'ä-lə-jē] -n, adj, adv

  1. a science dealing with the deformation and flow of matter
  2. the ability to flow or be deformed

rhe·om·e·ter [rē-'ä-mə-tər] -n

  1. an instrument for measuring flow (as of viscous substances)

rheo·stat ['rē-ə-,stat] -n, adj

  1. a resistor for regulating a current by means of variable resistances

rhe·sus monkey ['rē-səs-] -n

  1. a pale brown Asian macaque ( Macaca mulatta) often used in medical research called also rhesus rhesus macaque

rhet -abbr

  1. rhetoric

rhe·tor ['rē-,tȯr, 're-; 'rē-tər, 're-] -n

  1. rhetorician

rhet·o·ric ['re-tə-rik] -n

  1. : the art of speaking or writing effectively: as
  2. the study of principles and rules of composition formulated by critics of ancient times
  3. the study of writing or speaking as a means of communication or persuasion
  4. skill in the effective use of speech
  5. a type or mode of language or speech
  6. insincere or grandiloquent language
  7. verbal communication : discourse

rhe·tor·i·cal [ri-'tȯr-i-kəl, -'tär-] -adj, adv

  1. of, relating to, or concerned with rhetoric
  2. employed for rhetorical effect
  3. asked merely for effect with no answer expected
    • a rhetorical question
  4. given to rhetoric : grandiloquent
  5. verbal

rhet·o·ri·cian [,re-tə-'ri-shən] -n

  1. a master or teacher of rhetoric
  2. orator
  3. an eloquent or grandiloquent writer or speaker

rheum ['rüm] -n, adj

  1. a watery discharge from the mucous membranes esp. of the eyes or nose
  2. tears

rheu·mat·ic [ru̇-'ma-tik] -adj, adv

  1. of, relating to, characteristic of, or affected with rheumatism

rheumatic -n

  1. one affected with rheumatism

rheumatic fever -n

  1. an acute disease that occurs chiefly in children and young adults and is characterized by fever, by inflammation and pain in and around the joints, and by inflammatory involvement of the pericardium and heart valves

rheu·ma·tism ['rü-mə-,ti-zəm, 'ru̇-] -n

  1. any of various conditions characterized by inflammation or pain in muscles, joints, or fibrous tissue
    • muscular rheumatism
  2. rheumatoid arthritis

rheu·ma·toid [-,tȯid] -adj

  1. characteristic of or affected with rheumatoid arthritis

rheumatoid arthritis -n

  1. a usu. chronic autoimmune disease that is characterized esp. by pain, stiffness, inflammation, swelling, and sometimes destruction of joints

rheumatoid factor -n

  1. an autoantibody of high molecular weight that reacts against IgG immunoglobulins and is often present in rheumatoid arthritis

rheu·ma·tol·o·gy [,rü-mə-'tä-lə-jē, ,ru̇-] -n, adj

  1. a medical science dealing with rheumatic diseases

Rh factor [,är-'āch-] -n

  1. any of one or more genetically determined antigens present in the red blood cells of most persons and of higher animals and capable of inducing intense immunogenic reactions

rhin- -comb form

  1. nose
    • rhino plasty

rhi·nal ['rī-nᵊl] -adj

  1. of or relating to the nose : nasal

rhin·en·ceph·a·lon [,rī-(,)nen-'se-fə-,län, -lən] -n, adj

  1. the chiefly olfactory part of the forebrain

rhine·stone ['rīn-,stōn] -n, adj

  1. a colorless imitation stone of high luster made of glass, paste, or gem quartz

Rhine wine ['rīn-] -n

  1. a usu. white wine produced in the Rhine valley
  2. a wine similar to Rhine wine produced elsewhere

rhi·ni·tis [rī-'nī-təs] -n

  1. inflammation of the mucous membrane of the nose

rhi·no ['rī-(,)nō] -n

  1. money, cash

rhino -n

  1. rhinoceros

rhi·noc·er·os [rī-'näs-rəs, rə-, -'nä-sə-] -n

  1. any of a family (Rhinocerotidae) of large heavyset herbivorous perissodactyl mammals of Africa and Asia that have one or two upright keratinous horns on the snout and thick gray to brown skin with little hair

rhinoceros beetle -n

  1. any of various large chiefly tropical scarab beetles (subfamily Dynastinae) having projecting horns on thorax and head

rhi·no·plas·ty ['rī-nō-,plas-tē] -n

  1. plastic surgery on the nose usu. for cosmetic purposes

rhi·nos·co·py [rī-'näs-kə-pē] -n

  1. examination of the nasal passages

rhi·no·vi·rus [,rī-nō-'vī-rəs] -n

  1. any of a genus ( Rhinovirus) of picornaviruses including two (species Human rhinovirus Aand Human rhinovirus B) having numerous serotypes causing respiratory infections (as the common cold) in humans

rhiz- -comb form

  1. root
    • rhizo plane

rhi·zo·bi·um [rī-'zō-bē-əm] -n, adj

  1. any of a genus ( Rhizobium) of small heterotrophic soil bacteria capable of forming symbiotic nodules on the roots of leguminous plants and of there becoming bacteroids that fix atmospheric nitrogen

rhi·zoc·to·nia [,rī-,zäk-'tō-nē-ə] -n

  1. any of a form genus ( Rhizoctonia) of imperfect fungi that includes major plant pathogens

rhi·zoid ['rī-,zȯid] -n, adj

  1. a rootlike structure

rhi·zo·ma·tous [rī-'zō-mə-təs] -adj

  1. having, resembling, or being a rhizome
    • a rhizomatous perennial grass

rhi·zome ['rī-,zōm] -n, adj

  1. a somewhat elongate usu. horizontal subterranean plant stem that is often thickened by deposits of reserve food material, produces shoots above and roots below, and is distinguished from a true root in possessing buds, nodes, and usu. scalelike leaves

rhi·zo·plane ['rī-zə-,plān] -n

  1. the external surface of roots together with closely adhering soil particles and debris

rhi·zo·pod ['rī-zə-,päd] -n

  1. any of a superclass (Rhizopoda) of usu. creeping protozoans (as an amoeba or a foraminifer) having lobate or rootlike pseudopodia

rhi·zo·pus ['rī-zə-pəs, -,pu̇s] -n

  1. any of a genus ( Rhizopus) of mold fungi including some economically valuable forms and some plant or animal pathogens (as a bread mold)

rhi·zo·sphere [-,sfir] -n

  1. soil that surrounds and is influenced by the roots of a plant

rhi·zot·o·my [rī-'zä-tə-mē] -n

  1. the operation of cutting the anterior or posterior spinal nerve roots

Rhneg·a·tive [,är-,āch-'ne-gə-tiv] -adj

  1. lacking Rh factor in the blood

rho ['rō] -n

  1. the 17th letter of the Greek alphabet

rhod- -comb form

  1. rose : red
    • rhodo lite

rho·da·mine ['rō-də-,mēn] -n

  1. any of a group of yellowish-red to blue fluorescent dyes
  2. a brilliant bluish-red dye made by fusing an amino derivative of phenol with phthalic anhydride and used esp. in coloring paper and as a biological stain

Rhode Island Red -n

  1. any of an American breed of general-purpose domestic chickens having a long heavy body, smooth yellow or reddish legs, and rich brownish-red plumage

Rhode Island White -n

  1. any of an American breed of domestic chickens resembling Rhode Island Reds but having pure white plumage

Rhodes grass ['rōdz-] -n

  1. an African perennial grass ( Chloris gayana) widely cultivated as a forage grass esp. in dry regions

Rho·de·sian man [rō-'dē-zh(ē-)ən-] -n

  1. an extinct African hominid ( Homo sapiens rhodesiensis) having long limb bones and a cranial capacity like those of modern humans but with more prominent brow ridges and a larger face and palate

Rhodesian ridge·back [-'rij-,bak] -n

  1. any of an African breed of powerful long-bodied hunting dogs having a dense harsh short tan coat with a characteristic crest of reversed hair along the spine

Rhodes scholar ['rōd(z)-] -n

  1. a holder of one of numerous scholarships founded under the will of Cecil J. Rhodes that can be used at Oxford University for two or three years and are open to candidates from the Commonwealth of Nations and the U.S.

rho·di·um ['rō-dē-əm] -n

  1. a rare silvery-white hard ductile metallic element that is resistant to acids, occurs native but is usu. obtained from nickel ores, and is used esp. as a catalyst and in platinum alloys

rho·do·chro·site [,rō-də-'krō-,sīt] -n

  1. a rose-red mineral consisting essentially of manganese carbonate

rho·do·den·dron [,rō-də-'den-drən] -n

  1. any of a genus ( Rhododendron) of widely cultivated shrubs and trees of the heath family with alternate leaves and showy flowers
  2. one with leathery evergreen leaves as distinguished from a deciduous azalea

rho·do·lite ['rō-də-,līt] -n

  1. a pink or purple garnet used as a gem

rhodomontade [,rä-də-mən-'tād, ,rō-, -'täd] -n

(variant of rodomontade)

  1. a bragging speech
  2. vain boasting or bluster : rant

rho·do·nite ['rō-də-,nīt] -n

  1. a pale red triclinic mineral that consists essentially of manganese silicate and is used as an ornamental stone

rho·dop·sin [rō-'däp-sən] -n

  1. a red photosensitive pigment in the retinal rods of the eye of most vertebrates that is important in vision in dim light called also visual purple

rho·do·ra [rō-'dȯr-ə] -n

  1. an azalea ( Rhododendron canadense) of northeastern No. America that has spring-flowering pink blossoms

rhomb ['räm(b)] -n

  1. rhombus
  2. rhombohedron

rhomb- -comb form

  1. rhombus
    • rhomb encephalon

rhomb·en·ceph·a·lon [,räm-(,)ben-'se-fə-,län, -lən] -n

  1. hindbrain

rhom·bic ['räm-bik] -adj

  1. having the form of a rhombus
  2. orthorhombic

rhom·bo·he·dron [,räm-bō-'hē-drən] -n, adj

  1. a parallelepiped whose faces are rhombuses

rhom·boid ['räm-,bȯid] -n

  1. a parallelogram with no right angles and with adjacent sides of unequal length
  2. shaped somewhat like a rhombus or rhomboid

rhom·boi·de·us [räm-'bȯi-dē-əs] -n

  1. either of two muscles that lie beneath the trapezius muscle and connect the spinous processes of various vertebrae with the medial border of the scapula

rhom·bus ['räm-bəs] -n

  1. a parallelogram with four equal sides and sometimes one with no right angles

rhon·chus ['räŋ-kəs] -n

  1. a whistling or snoring sound heard on auscultation of the chest when the air channels are partly obstructed

Rhpos·i·tive [,är-,āch-'pä-zə-tiv, -'päz-tiv] -adj

  1. containing Rh factor in the red blood cells

rhu·barb ['rü-,bärb] -n

  1. any of a genus ( Rheum) of Asian plants of the buckwheat family having large leaves with thick succulent petioles often used as food
  2. the petioles of rhubarb
  3. the dried rhizome and roots of any of several rhubarbs (as Rheum officinaleand R. palmatum) grown in China and Tibet and used as a purgative and stomachic
  4. a heated dispute or controversy

rhumb ['rəm(b)] -n

  1. a line or course on a single bearing
  2. any of the points of the mariner's compass

rhumba ['rəm-bə, 'ru̇m-, 'rüm-] -n

(variant of rumba)

  1. a ballroom dance of Cuban origin in or time with a basic pattern of step-close-step and marked by a delayed transfer of weight and pronounced hip movements
  2. the music for this dance

rhumb line -n

  1. a line on the surface of the earth that follows a single compass bearing and makes equal oblique angles with all meridians called also loxodrome

rhus ['rüs] -n

  1. sumac

rhyme ['rīm] -n, adj

  1. rhyming verse
  2. poetry
  3. a composition in verse that rhymes
  4. correspondence in terminal sounds of units of composition or utterance (as two or more words or lines of verse)
  5. one of two or more words thus corresponding in sound
  6. : correspondence of other than terminal word sounds: as
  7. alliteration
  8. internal rhyme
  9. rhythm, measure
  10. to relate or praise in rhyming verse
  11. to put into rhyme
  12. to compose (verse) in rhyme
  13. to cause to rhyme : use as rhyme
  14. to make rhymes
  15. to compose rhyming verse
  16. to end in syllables that are rhymes
  17. to be in accord : harmonize

rhyme or reason -n

  1. good sense or reason

rhyme royal [-'rȯi(-ə)l] -n

  1. a stanza of seven lines in iambic pentameter with a rhyme scheme of ababbcc

rhyme scheme -n

  1. the arrangement of rhymes in a stanza or a poem

rhyme·ster ['rīm(p)-stər] -n

  1. an inferior poet

rhyming slang -n

  1. slang in which the word intended is replaced by a word or phrase that rhymes with it (as loaf of breadfor head) or the first part of the phrase (as loaffor head)

rhyn·cho·ce·pha·lian [,riŋ-kō-sə-'fāl-yən] -n, adj

  1. any of an order (Rhynchocephalia) of reptiles resembling lizards that includes the tuatara as the only living member

rhy·o·lite ['rī-ə-,līt] -n, adj

  1. a very acid volcanic rock that is the lava form of granite

rhythm ['ri-thəm] -n

  1. an ordered recurrent alternation of strong and weak elements in the flow of sound and silence in speech
  2. a particular example or form of rhythm
    • iambic rhythm
  3. the aspect of music comprising all the elements (as accent, meter, and tempo) that relate to forward movement
  4. a characteristic rhythmic pattern
    • rumba rhythm
  5. meter
  6. the group of instruments in a band supplying the rhythm called also rhythm section
  7. movement, fluctuation, or variation marked by the regular recurrence or natural flow of related elements
    • the rhythm s of country life
  8. the repetition in a literary work of phrase, incident, character type, or symbol
  9. a regularly recurrent quantitative change in a variable biological process
    • a circadian rhythm
  10. the effect created by the elements in a play, movie, or novel that relate to the temporal development of the action
  11. rhythm method

rhythm and blues -n

  1. popular music typically including elements of blues and African-American folk music and marked by a strong beat and simple chord structure

rhythm band -n

  1. a band usu. composed of schoolchildren who play simple percussion instruments (as rhythm sticks, sleigh bells, or tambourines) to learn fundamentals of coordination and music

rhyth·mic ['rith-mik] -adj, adv

  1. marked by or moving in pronounced rhythm
  2. of, relating to, or involving rhythm

rhyth·mic·i·ty [rith-'mi-sə-tē] -n

  1. the state of being rhythmic or of responding rhythmically

rhyth·mics ['rith-miks] -n pl but sing or pl in constr

  1. the science or theory of rhythms

rhyth·mist ['ri-thə-mist, 'rith-mist] -n

  1. one who studies or has a feeling for rhythm

rhyth·mize [-,mīz] -vt, n

  1. to order or compose rhythmically

rhythm method -n

  1. a method of birth control involving abstinence during the period in which ovulation is most likely to occur

rhythm stick -n

  1. one of a pair of plain or notched wood sticks that are struck or rubbed together to produce various percussive sounds and are used esp. by young children in rhythm bands

rhyt·i·dome ['ri-tə-,dōm, 'rī-] -n

  1. the bark external to the last formed periderm

rhy·ton ['rī-,tän] -n

  1. any of various ornate drinking vessels of ancient times typically shaped in part like an animal or animal's head