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Meaning of hypabyssal

hyp•a•byss•al

Pronunciation: (hip"u-bis'ul, hī"pu-), [key]
— adj. Geol.
  1. (of an igneous rock) intermediate in texture between coarse-grained intrusive rocks and fine-grained extrusive rocks.
  2. 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.