/ Dictionary / Index I isotac: Meaning and Definition of Find definitions for: i•so•tac Pronunciation: (ī'su-tak"), [key] — n. a line drawn on a map connecting all points where ice starts to melt at approximately the same period in spring. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. isostructural isotach Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language