What is "fourth person"

n. 1 (context grammar English) A variety of the third person sometimes used for indefinite referents, such as ''one'' in ''one shouldn't do that''. 2 (context linguistics English) grammatical person in some languages distinct from first person, second person, and third persons, semantically translated by one of them in English. For example, in Ojibwe, it is a variety of the third person used for a secondary, or obviative, third person.