Idiotic

прилагательное дурацкий, идиотский Например: They were idiotic to do that. — Они поступили по-идиотски. Синоним(ы): imbecile, stupid

Большой англо-русский словарь

Idiotic

also idiotical adjective 1. characterized by idiocy 2. showing complete lack of thought or common sense; foolishidiotically adverb

Merriam-Webster's Collegiate Dictionary