Fully aware; in a state of keeping up with current information about a topic; engaged wholeheartedly in a task or cause
With its plug properly connected to the electric plug socket.
Of a person: having obtained worldly experience, and lacking naiveté; cosmopolitan, worldly-wise.
Complicated, especially of complex technology.
Of art or other things: appealing to the tastes of an intellectual or sophisticated (sense 1) person; cerebral; also, cultured, elegant, refined.