have no idea | not have the faintest, first, etc. idea成語所屬單字ideahave no idea | not have the faintest, first, etc. ideahave no idea | not have the faintest, first, etc. idea — 慣用語慣用語1. To not know something at all.1.慣用語釋義完全不知道To not know something at all.例句I have no idea where my keys are.She hasn't the faintest idea how to cook.