au·thor·i·ty 
(ə-thôrĭ-tē, ə-thŏr-, ô-)
(ə-thôrĭ-tē, ə-thŏr-, ô-)n. pl. au·thor·i·ties
1.
a. The power to enforce laws, exact obedience, command, determine, or judge.
b. One that is invested with this power, especially a government or body of government officials: land titles issued by the civil authority.
2. Power assigned to another; authorization: Deputies were given authority to make arrests.
3. A public agency or corporation with administrative powers in a specified field: a city transit authority.
4.
a. An accepted source of expert information or advice: a noted authority on birds; a reference book often cited as an authority.
b. A quotation or citation from such a source: biblical authorities for a moral argument.
5. Justification; grounds: On what authority do you make such a claim?
6. A conclusive statement or decision that may be taken as a guide or precedent.
7. Power to influence or persuade resulting from knowledge or experience: political observers who acquire authority with age.
8. Confidence derived from experience or practice; firm self-assurance: played the sonata with authority.
[Middle English auctorite, from Old French autorite, from Latin auctōritās, auctōritāt-, from auctor, creator; see AUTHOR.]