Imbecility (noun)

1. The state or quality of being extremely stupid; the state or quality of showing a lack of intelligence or common sense.
2. The state or quality of having or showing a mental disability; the state or quality of having or showing characteristics of an imbecile.

Origin:

Early 19th century: from french imbécilité, from latin imbecillitas, from imbecillus (see imbecile).

Examples:

1. His imbecility was evident in his inability to understand basic instructions.
2. The imbecility of the plan was obvious to everyone in the room.
3. The company's financial struggles were the result of the imbecility of its management.
4. The imbecility of her argument was clear to all who heard it.
5. It was a moment of imbecility that he would later regret.