Mental impression is a concept that refers to the mental image or IDEA that one has of something. The term can be broken down into two crossword solutions: IDEA (4 letters) and PERCEPT (7 letters). IDEA is defined as a thought or suggestion as to a possible course of action, while PERCEPT is defined as an awareness or understanding of something. Together, these two words form the phrase mental impression, which is the mental image or IDEA that one has of something.