R R is the eighteenth letter of the English Alphabet, and an articulation sui generis, having little or no resemblance in pronunciation to any other letter. But from the position of the tongue in uttering it, it is commutable with l, into which letter it is changed in many words by the Spaniards and Portuguese, and some other nations; as l is also changed into r. It is numbered among the liquids and semi-vowels, and is sometimes called the canine letter. It is uttered with a guttural extrusion of the breath, and in some words, particularly at the end or after a labial and a dental letter, with a sort of quivering motion or slight jar of the tongue. Its English uses, which are uniform, may be understood by the customary pronunciation of rod, room, rose, bar, bare, barren, disturb, catarrh, free, brad, pride, drip, drag, drown.
In words which we have received from the Greek language, we follow the Latins, who wrote h after r, as the representative of the aspirated sound with which this letter was pronounced by the Greeks. It is the same in the Welsh language. But as the letter is not aspirated in English, h is entirely superfluous; rhapsody, rheum, rhetoric, being pronounced rapsody, reum, retoric.
As an abbreviation, R. in English, stands for rex, king, as George R.
As a numeral, R, in Roman authors, stands for 80, and with a dash over it, for 80,000. But in Greek, with a small mark over it, signifies 100, and with the same mark under it, it denoted 1000x100, or 100,000. In Hebrew, denoted 200, and with two horizontal points over it, 1000x200, or 200,000.
Among physicians, R. stands for recipe, take.

R n 1: a unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air [syn: roentgen, R] 2: (physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole [syn: gas constant, universal gas constant}, R] 3: the 18th letter of the Roman alphabet [syn: R, r] 4: the length of a line segment between the center and circumference of a circle or sphere [syn: radius, r]

R Three Rs said to have been given as a toast by Sir W. Curtis (died 1849).

R I. abbreviation 1. rabbi 2. radial 3. radical — used especially of a monovalent hydrocarbon radical 4. Rankine 5. Reaumur 6. recipe 7. registered trademark — often enclosed in a circle 8. regular 9. Republican 10. river 11. R-value II. certification mark — used to certify that a motion picture is of such a nature that admission is restricted to persons over a specified age (as 17) unless accompanied by a parent or guardian; compare g, NC-17, pg, PG-13

r abbreviation 1. radius 2. rain 3. range 4. rare 5. real 6. recto 7. red 8. repeat 9. rerun 10. resistance 11. right 12. roentgen 13. rook 14. rough 15. run

R
1.
n. (also r) (pl. Rs or R's) the eighteenth letter of the alphabet.
Phrases and idioms:
the r months the months with r in their names (September to April) as the season for oysters.
2.
abbr. (also R.)
1 Regina (Elizabeth R).
2 Rex.
3 River.
4 (also
Usage:
) registered as a trademark.
5 (in names of societies etc.) Royal.
6 Chess rook.
7 Railway.
8 rand.
9 Regiment.
10 Réaumur.
11 radius.
12 roentgen.

r
1.
n. (also r) (pl. Rs or R's) the eighteenth letter of the alphabet.
Phrases and idioms:
the r months the months with r in their names (September to April) as the season for oysters.
2.
abbr. (also R.)
1 Regina (Elizabeth R).
2 Rex.
3 River.
4 (also
Usage:
) registered as a trademark.
5 (in names of societies etc.) Royal.
6 Chess rook.
7 Railway.
8 rand.
9 Regiment.
10 Réaumur.
11 radius.
12 roentgen.

r.
abbr. (also r)
1 right.
2 recto.
3 run(s).
4 radius.

R \R\ ([aum]r). R, the eighteenth letter of English alphabet, is a vocal consonant. It is sometimes called a semivowel, and a liquid. See Guide to Pronunciation, [sect][sect] 178, 179, and 250-254. ``R is the dog's letter and hurreth in the sound.'' --B. Jonson. Note: In words derived from the Greek language the letter h is generally written after r to represent the aspirated sound of the Greek "r, but does not affect the pronunciation of the English word, as rhapsody, rhetoric. The English letter derives its form from the Greek through the Latin, the Greek letter derived from the Ph[oe]nician, which, it is believed, is ultimately of Egyptian origin. Etymologically, R is most closely related to l, s, and n; as in bandore, mandole; purple, L. purpura; E. chapter, F. chapitre, L. capitulum; E. was, were; hare, G. hase; E. order, F. ordre, L. ordo, ordinis; E. coffer, coffin. The three Rs, a jocose expression for reading, (w)riting, and (a)rithmetic, -- the fundamentals of an education.

R === [10] [10] Ed. Note: The editor apologizes for the character of the R's who have been famous.

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