authorisation

The noun has 4 meanings:

Meaning #1: a document giving an official instruction or command
  Synonyms: mandate, authorization

Meaning #2: the power or right to give orders or make decisions
  Synonyms: authority, authorization, dominance, say-so

Meaning #3: official permission or approval
  Synonyms: authority, authorization, sanction

Meaning #4: the act of conferring legality or sanction or formal warrant
  Synonyms: authorization, empowerment