folly

Synonyms for folly: foolishness, stupidity, idiocy, absurdity, imprudence, recklessness.

Definitions

Lack of good sense; foolishness.

A costly and foolish undertaking or investment.

A decorative building or structure built in a garden or park, typically for aesthetic purposes rather than practical use.

It would be pure folly to invest all of your savings in such a risky venture.

The king finally realized the folly of his decision to go to war without an army.