The Collaborative International Dictionary of English v.0.48:

Intrusive \In*tru"sive\, a.
   Apt to intrude; characterized by intrusion; entering without
   right or welcome.
   [1913 Webster]

   Intrusive rocks (Geol.), rocks which have been forced,
      while in a plastic or melted state, into the cavities or
      between the cracks or layers of other rocks. The term is
      sometimes used as equivalent to plutonic rocks. It is
      then contrasted with effusive or volcanic rocks. --
      In*tru"sive*ly, adv. -- In*tru"sive*ness, n.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Plutonic \Plu*ton"ic\, a. [Cf. F. plutonique. See Pluto.]
   1. Of or pertaining to Pluto; Plutonian; hence, pertaining to
      the interior of the earth; subterranean.
      [1913 Webster]

   2. Of, pertaining to, or designating, the system of the
      Plutonists; igneous; as, the Plutonic theory.
      [1913 Webster]

   Plutonic action (Geol.), the influence of volcanic heat and
      other subterranean forces under pressure.

   Plutonic rocks (Geol.), granite, porphyry, and some other
      igneous rocks, supposed to have consolidated from a melted
      state at a great depth from the surface. Cf. Intrusive
      rocks, under Intrusive.

   Plutonic theory. (Geol.) See Plutonism.
      [1913 Webster]