noun

• (uncountable) Power or right to make or enforce rules, give orders, or impose obligation; or a position having such power or right.
  "I have the authority to penalise the staff in my department, but not the authority to sack them."
• (plural) Persons, regarded collectively, who occupy official positions of power; police or law enforcement.
  "Authorities say the suspect fled on foot."
• (countable) A reliable, definitive source of information on a subject.
  "the world's foremost authority on orangutans"
• (uncountable) Status as a trustworthy source of information, reputation for mastery or expertise; or claim to such status or reputation.
  "Due to being inadequate for the deductive method of reasoning, the argument from authority is considered a logical fallacy."