mesothorium Hear it!

mesothorium Definition

meso·tho·rium (--t̸hôr′ē əm)

noun

  1. a radioactive isotope of radium (mesothorium 1), formed from thorium
  2. a radioactive isotope of actinium (mesothorium 2), formed from this isotope of radium

Etymology: ModL: see meso- & thorium