[in.tru.sion] n [ME, fr. MF, fr. ML intrusion-, intrusio, fr. L intrudere] (15c) 1: the act of intruding or the state of being intruded; esp: the act of wrongfully entering upon, seizing, or taking possession of the property of another
2: the forcible entry of molten rock or magma into or between other rock formations; also: the intruded magma