Radioactive material refers to any substance that contains unstable atoms that emit radiation. There are several synonyms for radioactive material, including isotopic substance, radioisotope, nuclear waste, radioactive waste, and radiological material. These substances are commonly found in nuclear power plants, medical facilities, and laboratories where they are used for research, diagnostics, and therapeutic purposes. Due to their potential harm to human health and the environment, radioactive materials are carefully regulated and stored in secure facilities. It is important to handle and dispose of these materials properly to minimize the risk of exposure to radiation.