The Collaborative International Dictionary
Extrusive
Extrusive \Ex*tru"sive\, a. [See Extrude.] (Geol.) Forced out at the surface; as, extrusive rocks; -- contrasted with intrusive.
Douglas Harper's Etymology Dictionary
extrusive
1816, from Latin extrus-, past participle stem of extrudere "thrust out; drive away" (see extrusion) + -ive. Related: Extrusively.
Wiktionary
extrusive
a. jut; extrude. n. (context geology English) Rock which has been formed through volcanic extrusion.
WordNet
extrusive
adj. of rock material; forced out while molten through cracks in the earth's surface [ant: intrusive]