The word "chemo" is a shortened version of chemotherapy - a medical treatment that uses chemical substances to destroy cancer cells. While "chemo" is a commonly used slang term for this type of treatment, there are a few synonyms and related terms that could be used. These include cancer drug therapy, cytotoxic therapy, and medical oncology. Additionally, some people might use the term "radiation" or "radiotherapy" to refer to a similar treatment option that uses high-energy radiation beams. It's important to note that each of these terms refer to different aspects of cancer treatment and should be used in the appropriate context.