intrusion Definition

intrusion
noun

1. An act or process of intruding, especially on someone else's property.

Thesaurus: encroachment, violation, infringement, interruption, interference, trespass, invasion; Antonym: withdrawal.
2. geol.
The forcing of molten magma under pressure into pre-existing rock.
3. A mass of igneous rock formed by the solidification of molten magma beneath the Earth's surface, after it has been forced into pre-existing rock.

Etymology: 14c: from Latin intrusio, from intrudere to thrust in.