There are several synonyms for the phrase "five-star admirals." One term that can be used is "fleet admirals," which refers to the highest rank in the United States Navy. Another synonym is "admiral of the fleet," which is similar to the rank of fleet admiral. The term "flag officer" is also applicable, which refers to any officer who holds a position that bears a flag or pennant. In addition, the term "admiralty" can be used to describe the highest levels of naval leadership and command. Whatever the term used, it signifies the highest level of rank and authority in the naval hierarchy.