What does "actinium" mean?

A radioactive, metallic chemical element (symbol: Ac) with an atomic number of 89; found in uranium ores.

What is a synonym for "actinium"?

Common synonyms include: ac, atomic number 89.

/ækˈtɪniəm/ noun

noun ·Rare ·Advanced level

Noun

1
A radioactive, metallic chemical element (symbol: Ac) with an atomic number of 89; found in uranium ores. uncountable, usually
2
a radioactive element of the actinide series; found in uranium ores wordnet

"Actinium is a radioactive element."

Borrowed from French actinium. actin- + -ium.