无力

powerless / lacking strength

not to have / no / none / not / to lack / un- / -less

power / force / strength / ability / strenuously

weakly and without strength (idiom); dispirited

unable to turn around a hopeless situation (idiom) / to fail to save the situation

myasthenia gravis (medicine)

feeling of powerlessness / sense of helplessness

pale and feeble / powerless