The term NAVAL OFFICER can be abbreviated in a variety of ways. ENS (3 letters) stands for Ensign, which is the lowest commissioned rank in the United States Navy and Coast Guard. CMDR (4 letters) stands for Commander, which is a senior OFFICER rank in the U.S. Navy and Coast Guard. ADM (3 letters) stands for Admiral, which is the highest commissioned rank in the U.S. Navy and Coast Guard. COM (3 letters) stands for Commodore, which is a senior naval rank in the U.S. Navy and Coast Guard. COMM (4 letters) stands for Commodore, which is a senior naval rank in the U.S. Navy and Coast Guard. COMR (4 letters) stands for Commodore, which is a senior naval rank in the U.S. Navy and Coast Guard.