in·cur·sion 
(ĭn-kûrzhən, -shən)
(ĭn-kûrzhən, -shən)n.
1. An aggressive entrance into foreign territory; a raid or invasion.
2. The act of entering another's territory or domain.
3. The act of entering or running into: homes damaged by the incursion of floodwater.
[Middle English, from Old French, from Latin incursiō, incursiōn-, from incursus, past participle of incurrere, to run upon; see INCUR.]