FULL (5 letters) The term 'booked solid' is a phrase used to describe a situation where something is completely FULL or BUSY. It can be used to describe a hotel, restaurant, or any other place that is completely booked with no more room for customers. The crossword solutions for this term are BUSY (4 letters) and FULL (5 letters). This phrase is often used to describe a situation where there is no more room for people or things, and it implies that the place is completely occupied.