What does "perjure" mean?

Perjure: To make a false oath to; to deceive by oaths and protestations. [Obs.] And with a virgin innocence did pray For me, that perjured her. J. Fletcher. These words have been used interchangeably; but there is a tendency to restrict perjure to that species of forswearing which constitutes the crime of perjury at law, namely, the willful violation of an oath administered by a magistrate or according to law.