Meaning of plutonism

plu•to•nism

Pronunciation: (plt'n-iz"um), [key]
— n. Geol.
  1. the intrusion of magma and associated deep-seated processes within the earth's crust.
  2. (often cap.) the disproven theory that all rocks formed by solidification of a molten mass, promulgated by Scottish geologist James Hutton (1726–97).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.