/ Dictionary / Index I isopach: Meaning and Definition of Find definitions for: i•so•pach Pronunciation: (ī'su-pak"), [key] — n. Geol. a line drawn on a map connecting all points of equal thickness of a particular geologic formation. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. iso-osmotic isopachous Related Content Daily Word Quiz: cetacean Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language