1) Eruptive 2) Of rock material 3) Pertaining to extrusion 4) Tending to extrude 5) Volcanic 1) Eruptive 
Extrusive refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. This is as opposed to intrusive rock formation, in which magma does not reach the surface. The main effect of extrusio...
mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff.
• (a.) Forced out at the surface; as, extrusive rocks; -- contrasted with intrusive.
Sunset Crater National Monument: a cinder cone, composed of extrusive rock. Credit: USGS Descriptive of igneous rocks that have erupted onto the surface. Extrusive, or volcanic, igneous rock is produced when magma exits and cools outside of, or very near the Earth's surface. These are the rocks ...
Igneous rocks that crystallize at Earth's surface.
Ex·tru'sive adjective [ See Extrude .] (Geol.) Forced out at the surface; as, extrusive rocks; -- contrasted with intrusive . 
Rocks that form on the surface from molten lava. Antonym of intrusive.
Igneous. Antonym of intrusive.
Igneous. Antonym of intrusive.
[adj] - (geology) of rock material
extrusive 1. Tending to push or thrust out. 2. Tending to protrude or project. 3. Derived from magma poured out or ejected at the earth's surface; a reference to igneous rocks. 4. 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.
relating to lava -- i.e., magma ejected out onto the Earth's surface; also applied to volcanic rocks formed from lava. 
adjective of rock material; forced out while molten through cracks in the earth`s surface
Pertaining to igneous rocks or features formed from lava released on the Earth
(igneous) rocks formed by eruptions at the Earth's surface (see volcanic).
tending to extrude. · pertaining to extrusion. · 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.