Feeblemindedness is a condition that affects cognitive abilities.

She feeblemindedly agreed to go along with their plan.

The feeblemindednesses of the students were evident in their inability to grasp basic concepts.

She struggled to lift the heavy box, her feeblesome arms trembling under the weight.

He is the feeblest-minded person I have ever met.

He is often underestimated because he is feebler-minded.