intrusion

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act of intruding or the condition of being intruded on.
• noun An inappropriate or unwelcome addition.
• noun The forcing of molten rock into an earlier formation.
• noun The rock mass produced by an intrusive process.

from The Century Dictionary.

• noun The act of intruding; the act of entering without warrant or justification; unbidden, unwelcome, or unfit entrance into or upon anything.
• noun Specifically, in law: A wrongful entry after the determination of a particular estate, say for life, and before the freehold remainderman or reversioner can enter.
• noun In English law, any trespass committed on the public lands of the crown, as by entering thereon without title, holding over after a lease is determined, taking the profits, cutting down timber, and the like.
• noun Usurpation, as of an office.—
• noun A thrusting or pushing in, as of something out of place; irregular or abnormal entrance or irruption: as, an intrusion of foreign matter; the intrusion of extrinsic rocks or dikes in a geological formation. See intrusive rocks, under intrusive.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act of intruding, or of forcing in; especially, the forcing (one's self) into a place without right or welcome; encroachment.
• noun (Geol.) The penetrating of one rock, while in a plastic or metal state, into the cavities of another.
• noun (Law) The entry of a stranger, after a particular estate or freehold is determined, before the person who holds in remainder or reversion has taken possession.
• noun (Scotch Ch.) The settlement of a minister over a congregation without their consent.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The forcible inclusion or entry of an external group or individual; the act of intruding.
• noun geology Magma forced into other rock formations; the rock formed when such magma solidifies.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun rock produced by an intrusive process
• noun the forcing of molten rock into fissures or between strata of an earlier rock formation
• noun any entry into an area not previously occupied
• noun entrance by force or without permission or welcome
• noun entry to another's property without right or permission