/ Dictionary / Index D diametral: Meaning and Definition of Find definitions for: di•am•e•tral Pronunciation: (dī-am'i-trul), [key] — adj. of a diameter. forming a diameter. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diametral (Thesaurus) diameter diametrical Related Content Daily Word Quiz: reclusive Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language