/ Dictionary / Index B birectangular: Meaning and Definition of Find definitions for: bi•rec•tan•gu•lar Pronunciation: (bī"rek-tang'gyu-lur), [key] — adj. Geom. having two right angles. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. bird watcher birefringence Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language