Hipbone is the common term for the coxal bone that forms the hip. However, there are several synonyms for hipbone that are used interchangeably. The most common alternative term is the innominate bone, which is technically correct but not widely used outside of medical contexts. The pelvic bone is also a synonym for hipbone, as it refers to the entire bone structure that makes up the pelvic girdle. Some other terms used synonymously for hipbone include the os coxae, hip joint, and acetabulum. Overall, these terms all refer to the same essential structure and can be used interchangeably depending on the context.