Plu-tōn'ic, a.

a. [Fr. Plutonique. See PLUTO.]

1. Pertaining to Pluto; hence, pertaining to the interior of the earth; subterranean.
2. Pertaining to, or designating, the system of the Plutonists; igneous; as, the Plutonic theory.

Plutonic action (Geol.), the influence of volcanic heat and other subterranean causes under pressure. — Plutonic rocks (Geol.), granite, porphyry, and other igneous rocks, supposed to have consolidated from a melted state at a great depth from the surface. Lyell.