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]