noun, na-adjective
idle and incompetent; accomplishing nothing and lacking ability
A yojijukugo describing a person who does nothing worthwhile and has no useful skills. Often used as a self-deprecating or critical description.
彼は自分を無為無能な人間だと言った。
He called himself an idle and incompetent person.
無為無能のまま一生を終えたくない。
I don't want to end my life remaining idle and incompetent.
無為 means 'idleness' or 'inactivity', but 無為無能 combines it with incompetence to emphasize both uselessness and lack of action.
A yojijukugo combining 無為 (idleness, doing nothing) and 無能 (incompetence, lack of ability). The exact historical origin is uncertain, but it follows a common four-character pattern of pairing two negative qualities.