Here are different ways to define failures:

☛ The condition or fact of not achieving the desired end or ends: the failure of an experiment.

☛ One that fails: a failure at one's career.

☛ The condition or fact of being insufficient or falling short: a crop failure.

☛ A cessation of proper functioning or performance: a power failure.

☛ Nonperformance of what is requested or expected, omission: failure to report a change of address.

☛ The act or fact of failing to pass a course, test or assignment.

☛ A decline in strength or effectiveness.

☛ The act or fact of becoming bankrupt or insolvent.