Imbecility

Part of speech: noun (n.)

The quality of being imbecile; weakness; feebleness, esp. of mind. Cruelty . . . argues not only a depravedness of nature, but also a meanness of courage and imbecility of mind. Sir W. Temple.

Synonyms: Debility; infirmity; weakness; feebleness; impotence. See Debility.