Having no idea can be expressed in two ways: CLUELESS (8 letters) and Drawing a Blank (13 letters). CLUELESS is an informal term used to describe someone who has no knowledge or understanding of a particular situation. Drawing a Blank is another way of expressing the same sentiment, but it implies that the person is unable to think of anything related to the situation. Both terms are often used to describe someone who is completely unaware of what is going on around them.