noun

• The act of varying or the state of being variable.
• A difference between what is expected and what is observed; deviation.
• The state of differing or being in conflict.
• An official permit to do something that is ordinarily forbidden by regulations.
• (law) A discrepancy between two legal documents.
• (law) A departure from a cause of action originally in a complaint.
• (statistics) The second central moment in probability.
• (physics, chemistry, biology) The number of degrees of freedom in a system.
• (computing, programming) Covariance and contravariance generally.