A key ring is a small metal or plastic ring that holds multiple keys together. It is often used to keep track of multiple keys, such as house keys, car keys, and office keys. The term 'key ring' can also refer to the collection of keys held together by the ring. The crossword solution for the term 'key ring' is ATOLL, which is a ring-shaped coral reef or island. An ATOLL is typically formed by coral growth around a central lagoon. Atolls are found in tropical regions and are often surrounded by shallow waters.