Covert Action: According the the Department of Defense Dictionary of Military and Associated Terms, covert action is “an operation that is so planned and executed as to conceal the identity of or permit plausible denial by the sponsor.” It is a “special activity”, both political and military, that the US Government could legally deny. The CIA is normally the only US Government agency legally allowed to carry out covert action.
Espionage: Any action taken by a government or individual to obtain information that is considered classified or confidential without the express permission of the keeper of that information.
Intelligence: Any information, data or statistic – usually classified – regarding another country, nation or individual.
Spy: An agent who engages in the act of espionage, intelligence gathering or any type of covert action.