n (linguistics|with 'the') The words, word-forms, and grammatical structures, taken collectively, that are normally used of people or things other than the speaker or the audience.
n (grammar) the form of a verb used when the subject of a sentence is not the audience or the one making the statement. In English, pronouns used with the third person include he, she, it, one, they, and who.
n A form of narrative writing using verbs in the third person in order to give the impression that the action is happening to another person.
n (legal) Someone not associated with a particular matter; a third party.