What it means
Perjury is the criminal offence of knowingly giving false evidence after taking an oath or making an affirmation to tell the truth. It applies both to spoken evidence in court and to sworn written evidence such as affidavits. Because the justice system depends on truthful evidence, perjury carries significant penalties, including imprisonment.
How it's used
When bank records contradicted his sworn affidavit, the husband risked a perjury charge for lying about his income.