WORD MEANING
Actinium meaning
ak-TIN-ee-um · noun
A radioactive chemical element with the symbol Ac and atomic number 89, used primarily in scientific research.
See all 16 words from the September 10, 2026 puzzle →Other meanings
A rare earth metal found in uranium ores.
A source of neutrons in nuclear reactors.
Actinium is primarily known as a chemical element but may appear in scientific or educational contexts.
Examples
Actinium is a radioactive element used in some types of radiation therapy.
The scientist studied the properties of actinium in the laboratory.