Bible Dictionaries
Mesothorium

Webster's Dictionary

(n.) A radioactive product intermediate between thorium and radiothorium, with a period of 5.5 years.

Bibliography Information
Webster, Noah. Entry for 'Mesothorium'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​m/mesothorium.html. 1828.