Rectally is a medical term often used to describe procedures or medications that are administered through the rectum. However, there are several synonyms that can be used in place of rectally to describe the same process or action. The term per rectum (PR) is commonly used in the healthcare industry to describe procedures done through the rectum. The phrase anally is also another synonym for rectally. However, it is more commonly used in informal settings. Other synonyms for rectally include through the back passage, by the bottom, and through the anus. It's important to note that these terms are solely used in the medical context.