Defining biologicalinvasions is challenging due in part to the proliferation of terms, especially among biological disciplines, that usually describe a set of ranging and different concepts. Depending on the author, a species in the invasion might be referred to as: alien, exotic, invasive, non-indigenous, imported, weedy, introduced, nonnative versus naturalized, endemic or indigenous. Some of the terms employed evoke anthropocentric concepts such as aggression, assault, and attack, which have normative implications. These implications and the lack of consistent uses of terms contribute to confusion.

Invasive species in general are defined as species that occupy or are in the process of occurring in regions where they have not been present historically. Specifically, invasive species are defined by their origin and distribution. An invasive species might spread into ...