foolheaded

Example:The stupid decision to skip the final exam cost him his grade.

Definition:Lacking intellectual capacity; unintelligent; foolish.

Example:His dumb mistake of not bringing a coat resulted in him getting cold.

Definition:Dull or stupid; lacking in intellectual ability.

Example:The silly idea of wearing sunglasses at night in a dark forest was not a good one.

Definition:Characterized by lack of sense or sound judgment; foolish.