idiocy
n. C1 Advanced US //ˈɪdiəsi// UK //ˈɪdɪˌɒsi// id·io·cy
n. the quality of being very foolish or lacking common sense. It is a strong word that people use when they are very angry or frustrated with someone's behavior.
n. the quality of being extremely foolish or lacking in intelligence. Often used in a pejorative sense to describe a person's behavior or a specific action.
His idiocy made the whole project a total failure.
The manager was furious at the employee's idiocy, which had caused a major delay in the delivery.
While the plan was technically sound, the idiocy of the team's execution rendered it completely ineffective in the eyes of the board.
From French idiotie, from Old French idiot. Displaced earlier idiotacy, idiotry. Equivalent to idiot + -cy. By surface analysis, idio- + -cy.