/ Dictionary / Index H hypabyssal: Meaning and Definition of Find definitions for: hyp•a•byss•al Pronunciation: (hip"u-bis'ul, hī"pu-), [key] — adj. Geol. (of an igneous rock) intermediate in texture between coarse-grained intrusive rocks and fine-grained extrusive rocks. noting any of various minor intrusions, as dikes and sills, that have crystallized under conditions intermediate between plutonic and extrusive. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hyp hypaesthesia Related Content Daily Word Quiz: immense Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language