Tumour is a medical term that is widely understood to mean an abnormal growth of cells in the body. However, there are several synonyms for this word that can be used interchangeably in medical terminology. These synonyms include neoplasm, lesion, mass, growth, lump, and cyst. Each of these words refers to an abnormal cellular growth, however, they may differ in their characteristics such as size, location or type. For instance, a neoplasm is a broad term that refers to any abnormal growth while a cyst is a fluid-filled growth. It is important to use accurate medical language when communicating about health issues to ensure that there is no confusion or misunderstanding.