The Collaborative International Dictionary of English v.0.48:

Perjury \Per"ju*ry\, n.; pl. Perjuries. [L. perjurium. See
   Perjure, v.]
   1. False swearing.
      [1913 Webster]

   2. (Law) At common law, a willfully false statement in a fact
      material to the issue, made by a witness under oath in a
      competent judicial proceeding. By statute the penalties of
      perjury are imposed on the making of willfully false
      affirmations.
      [1913 Webster]

   Note: If a man swear falsely in nonjudicial affidavits, it is
         made perjury by statute in some jurisdictions in the
         United States.
         [1913 Webster]