Definition of "intrusive"

Tending to intrude; doing that which is not welcome; interrupting or disturbing; entering without permission or welcome.  examples

(geology) Of rocks: forced, while in a plastic or molten state, into the cavities or between the cracks or layers of other rocks.

(linguistics) epenthetic  examples

(geology) An igneous rock that is forced, while molten, into cracks or between other layers of rock