It is an idiom meaning disobedience, rebellion and defiance, but originally it meant meigen, an act of stringing a bow for purifying evil spirit, devil and disgrace.
-反抗や謀反（むほん）や楯突くことであるが、本来は鳴弦のことで弓の弦を引いて鳴らす事により悪霊や魔や穢れを祓う行為。