1 [uncountable and countable]PM when the army of one country enters another country by force, in order to take control of it
2 [countable] the arrival in a place of a lot of people or things, often where they are not wanted :
the annual invasion of teenagers for the Glastonbury Festival
the annual invasion of teenagers for the Glastonbury Festival3 a situation in which someone tries to find out details about another person's private affairs in a way that is upsetting and often illegal
