The term 'letterhead design' refers to the design of a letterhead, which is typically used for official documents and correspondence. The crossword solution for this term is 'LOGO, ' which stands for 'logotype, ' which is a graphic representation of a company's name or trademark. A LOGO is often used as part of a letterhead design, and it is usually placed at the top of the page. It is meant to be a visual representation of the company's identity and can be used to create a professional and recognizable look.