Enter a clue or pattern or both:
The Clue
Radioactive elements (9 letter answer)
The Answer
ACTINIDES
Tags
Notes
The answer ACTINIDES is so rare that it appears less than once every 2500 puzzles.
Definition
ACTINIDE as a noun:
1. (actinoid, actinide, actinon) = any of a series of radioactive elements with atomic numbers 89 through 103