/ Dictionary / Index D directrix: Meaning and Definition of Find definitions for: di•rec•trix Pronunciation: (di-rek'triks, dī-), [key] — pl. di•rec•trix•es, di•rec•tri•ces a fixed line used in the description of a curve or surface. See diag. under a directress. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. directress direct sum Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language