Answer the following question given this paragraph: 

A radioactive isotope, or radioisotope, has atoms with unstable nuclei. The unstable nuclei naturally decay, or break down, by losing energy and particles of matter to become more stable. If they gain or lose protons as they decay, they become different elements. Over time, as the nuclei continue to decay, less and less of the original radioisotope remains.


Q: What is another name for a radioactive isotope?


A:
radiostope