Definition of "invasion"

invasion

/ɪnˈveɪʒən/

noun
countable and uncountable, plural invasions
1. A military action consisting of armed forces of one geopolitical entity entering territory controlled by another such entity, generally with the objective of conquering territory or altering the established government.
  Quotations
  Yeh actually works in marketing, and his weapon is a replica -- but he is spending the weekend attending an urban warfare workshop to prepare for what he sees as the very real threat of a Chinese invasion.
  2022 July 7, “Inspired by Ukraine, civilians study urban warfare in Taiwan”, in France 24‎, archived from the original on 07 July 2022‎
2. The entry without consent of an individual or group into an area where they are not wanted.
3. (medicine) The spread of cancer cells, bacteries and such to the organism.
4. (surgery) The breaching of the skin barrier.