Pronunciation: (ik-strOO'siv, -ziv), [key]
1. tending to extrude.
2. pertaining to extrusion.
3. Also,effusive. Geol.noting or pertaining to a class of igneous rocks that have been forced out in a molten or plastic condition upon the surface of the earth.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.