Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun atomic_number_90

1 sense of atomic number 90

Sense 1
thorium, Th, atomic number 90 -- (a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands)
       => metallic element, metal -- (any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.)