perjurer

Definition from Nolo’s Plain-English Law Dictionary

A person who intentionally lies while under an oath administered by a notary public, court clerk, or other official, and thus commits the crime of perjury. A perjurer may commit perjury in oral testimony or by signing or acknowledging a written legal document (such as an affidavit, declaration under penalty of perjury, deed, license application,or tax return) knowing the document contains false information. (See also: perjury)

Definition provided by Nolo’s Plain-English Law Dictionary.