What is "obviative"

a. Describing such a marker n. (context linguistics English) A grammatical marker in the Algonquian (and some other) languages for a third person other than the principal

Obviative ( abbreviated ) third person is a grammatical-person marking that distinguishes a non- salient (obviative) third-person referent from a more salient ( proximate) third-person referent in a given discourse context. The obviative is sometimes referred to as the "fourth person".