[ik-stroo-siv, -ziv]
tending to extrude.
pertaining to extrusion.
Also, effusive. Geology. 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.

1810–20; extrus(ion) + -ive

nonextrusive, adjective
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World English Dictionary
extrusive (ɪkˈstruːsɪv)
1.  tending to extrude
2.  Compare intrusive (of igneous rocks) formed from magma issuing from volcanoes or cracks in the earth's crust; volcanic

Collins English Dictionary - Complete & Unabridged 10th Edition
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Word Origin & History

1816, from L. extrus-, pp. stem of 'extrudere (see extrusion) + -ive. Related: Extrusively.
Online Etymology Dictionary, © 2010 Douglas Harper
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Example sentences
Extrusive rocks are more difficult to clearly identify because the mineral
  grains are typically invisible.
Igneous rocks are divided into two groups, intrusive or extrusive, depending
  upon where the molten rock solidifies.
These rocks are characterized as either extrusive or intrusive.
Extrusive rocks are made of small, often microscopic crystals, which indicate
  rapid cooling and little time for crystal growth.
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