in·tru·sion /in-'trü-zhən/ n
1 a: the entry at common law of a stranger after a particular estate of freehold is determined before the person who holds it in remainder or reversion has taken possession
b: the act of wrongfully entering upon, seizing, or taking possession of the property of another
2: a trespassing on or encroachment upon something (as a right)
the Fourth Amendment demands that the showing of justification match the degree of intrusion — Berger v. New York, 388 U.S. 41 (1968)
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.