Fast Fact: Words have meaning: Merriam Webster definition of “invasion” January 4, 2019 By Bill Buckler Image: Merriam Webster invasion noun in·va·sion | \in-ˈvā-zhən \ Definition of invasion 1: an act of invading especially : incursion of an army for conquest or plunder 2: the incoming or spread of something usually hurtful Here. Share this:FacebookX