mesothorium

American

[mez-oh-thawr-ee-uhm, -thohr-, mes-, mee-zoh-, -soh-] / ˌmɛz oʊˈθɔr i əm, -ˈθoʊr-, ˌmɛs-, ˌmi zoʊ-, -soʊ- /

noun

Chemistry.

one of two radioactive decay products of thorium, an isotope of radium or actinium.

mesothorium British

/ ˌmɛsəʊˈθɔːrɪəm /

noun

obsolete physics either of the two radioactive elements which are decay products of thorium. Mesothorium I is now called radium-228. Mesothorium II is now called actinium-228

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023