quick or skillful or adept in action or thought; "an exceptionally adroit pianist"; "an adroit technician"; "his adroit replies to hecklers won him many followers"; "an adroit negotiator"
skillful (or showing skill) in adapting means to ends; "cool prudence and sensitive selfishness along with quick perception of what is possible--these distinguish an adroit politician"; "came up with a clever story"; "an ingenious press agent"; "an ingenious scheme"
based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence