Forswear :: Forswear (v. i.) To reject or renounce upon oath; hence, to renounce earnestly, determinedly, or with protestations..
Forswear :: Forswear (v. i.) To swear falsely; to commit perjury.
Forswearer :: Forswearer (n.) One who rejects of renounces upon oath; one who swears a false oath.