At the summit is a phrase that is used to describe a situation where someone or something has reached the highest point or level. It can be used to describe a person who has achieved success, a group of people who have come together to discuss an important issue, or a mountain peak that has been reached. The crossword solutions for this phrase are ATOP (4 letters), ONTOP (5 letters), and TOPMOST (7 letters). All three of these words refer to the highest point or level that can be reached.