- utterly senseless or foolish behavior; a stupid or foolish act, statement, etc.: All this talk of zombies coming to attack us is pure idiocy.
- (no longer in technical use; considered offensive) an intellectual disability, previously classified in a now obsolete rubric of developmental disorders as having a mental age of less than three years old and an intelligence quotient under 25.
- severe mental retardation
- foolishness or senselessness; stupidity
- a foolish act or remark
