In*tru"sive (?), a. Apt to
intrude; characterized by intrusion; entering without right or
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. --