[n] (informal) a shrewd or unscrupulous person who knows how to circumvent difficulties
[n] an agent that operates some apparatus or machine; "the operator of the switchboard"
[n] someone who owns or operates a business; "who is the operator of this franchise?"
[n] a speculator who trades aggressively on stock or commodity markets
[n] (mathematics) a symbol that represents a function from functions to functions; "the integral operator"