noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   A radioactive isotope of thorium, ²²⁸₉₀Th, having a half-life of 1.9 years; it occurs naturally in small amounts, as member of the thorium-232 decay chain. uncountable
2. 2
   radioactive isotope of thorium with mass number 228 wordnet

Synonyms

All synonyms

radiothorium