oneself synonym, oneself definition | Thesaurus. perjure (oneself) oneself. Oneself is a third person singular reflexive pronoun. 1 pron A speaker or writer uses oneself as the object of a verb or preposition in a clause where `oneself' meaning `me' or `any person in general' refers to the same person as the subject of the verb. FORMAL To work one must have time to oneself.