/ Dictionary / Index D diameter: Meaning and Definition of Find definitions for: di•am•e•ter Pronunciation: (dī-am'i-tur), [key] — n. a straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end. a straight line passing from side to side of any figure or body, through its center. the length of such a line. the width of a circular or cylindrical object. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diameter (Thesaurus) diamantiferous diametral Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language