Perjury, also known as forswearing,'s the willful act of swearing a false oath or affirmation to tell the truth, whether spoken or in writing, concerning matters material to a judicial proceeding. That's, the matter lied about would affect the outcome of the case. It isn't considered perjury, for example, to lie about one's age, unless that person's age's a key factor in proving the case, such as eligibility for old age retirement benefits. Perjury's considered a serious offense as it can be us… (More on Perjury)