Definition of
R
- (noun, quantity) a unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air
- (noun, quantity) (physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole
- (noun, communication) the 18th letter of the Roman alphabet
- (noun, attribute) the length of a line segment between the center and circumference of a circle or sphere
via WordNet, Princeton University
Synonyms of R
Alternate forms of R
Hyponyms: radius of curvature, semidiameter
Hypernyms: alphabetic character, constant, length, letter, letter of the alphabet, radioactivity unit
Origin of the word R
- In a circle, meaning "registered (trademark)," first incorporated in U.S. statues 1946. Three Rs (1825) said to have been given as a toast by Sir W. Curtis (1752-1829). R&R "rest and relaxation," first recorded 1953, Amer.Eng.; R&B "rhythm and blues" (type of popular music) first attested 1949, Amer.Eng. more
via Online Etymology Dictionary, ©2001 Douglas Harper