1 An action, event, or force that produces or contributes to an effect or result. Also called causation. 2 The ground or reason for a choice made or action taken. 3 A matter to be decided by a court. but-for cause. A cause without which the events or results that follow could not occur. Also called causa sine qua non. See also but-for test, causa,and proximate cause. concurrent cause. 1One of multiple causes that simultaneously produce an effect or result that no single cause could. 2 One of ...