/ Dictionary / Index R radial motion: Meaning and Definition of Find definitions for: ra'dial mo'tion Pronunciation: [key] — Astron. Astron. the component of the motion of a star away from or toward the earth along its line of sight, expressed in miles or kilometers per second and determined by the shift in the wavelength of light emitted by the star. Also calledCf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. radial keratotomy radial saw Related Content Daily Word Quiz: mamba Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language