THE 18th letter and 14th consonant of , the English alphabet. It is a lingual and a liquid or semi-vowel, being pronounced both before and after most other consonants. It is found in all languages except the Chinese and the tongues of some of the North American Indians. The Romans borrowed it from the Greek rho (P, ρ), which is derived from the Hebrew and Phoenician resh. It is one of the last which children learn to pronounce, and those who have been engaged in teaching persons deaf from birth to articulate find the greatest difficulty in conveying any idea of its sound to their pupils. The most common mode of pronouncing it is by an expiration while the tongue touches the roof of the mouth with a tremulous motion, as in the word rhetoric. The tremulous sound is more distinct in the Spanish rr, which indeed is not readily learned by Englishmen or Americans. It is frequently exaggerated by the Irish and softened down by the English, who are more easily distinguished by their peculiar pronunciation of this letter than by that of any other. - The Romans often added an r to words which they borrowed from the Greek, as υυός, nurus; μύαξ, murex; and on the other hand they often dropped it from the nominative case of nouns and retained it in the oblique cases, as oes, oeris; os, oris.

It was interchanged sometimes with s, the words arena, laribus, pignora, Furii, Valerii, and Papirii having been anciently written asena, lasibus, pignosa, Fusii, Valesii, and Papisii. The same change is observed in some modern languages, as Eng. hare, Ger. haase; Eng. was, Ger. war. It is most frequently interchanged however with l. The, Chinese, who cannot pronounce r, always use I in its place; the Japanese do exactly the reverse. (See L.) - As a Roman numeral R denotes 80, or with a dash over it R 1400100 80,000. The Greek P with a dash over it stands for 100, and with a dash under it for 100,000. As an abbreviation, R signifies Roma, Romanus; R. P., res publica; R. C., Roma condita.