excuse

Concise Oxford English Dictionary © 2008 Oxford University Press:
excuse

▶verb /ɪkˈskjuːz, ɛk-/ 

• 1 try or serve to justify (a fault or offence); mitigate.

  ■ forgive (a fault or offence, or a person committing one).

• 2 release from a duty or requirement.

  ■ (used in polite formulas) allow to leave a room or gathering.

  ■ (excuse oneself) say politely that one is leaving.

▶noun /ɪkˈskjuːs, ɛk-/ 

• 1 a defence or justification of a fault or offence.

• 2 something said to conceal the real reason for an action.

• 3 (an excuse for) informal a poor or inadequate example of.

– phrases
excuse me a polite apology for an interruption, asking someone to move, etc.

■ N. Amer. used to ask someone to repeat a remark.

– derivatives
excusable adjective,
excusably adverb,
excusatory adjective.

– origin ME: from OFr. escuser (v.), from L. excusare ‘to free from blame’, from ex- ‘out’ + causa ‘accusation, cause’.