#1 mastermind v. [engineer, direct, organize, organise, orchestrate] plan and direct (a complex undertaking); "he masterminded the robbery". wn #2 mastermind n. [originator, conceiver] someone who creates new things. wn #3 mastermind n. [genius, brain, brainiac, Einstein] someone who has exceptional intellectual ability and originality; "Mozart was a child genius"; "he's smart but he's no Einstein". wn