/ Dictionary / Index I isosceles: Meaning and Definition of Find definitions for: i•sos•ce•les Pronunciation: (ī-sos'u-lēz"), [key] — adj. (of a straight-sided plane figure) having two sides equal:See diag. under an isosceles triangle; an isosceles trapezoid. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: isosceles (Thesaurus) isorhythm isoseismic Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language