Enter a clue or pattern or both:
The Clue
Decaying substances (7 letter answer)
The Answer
RADIUMS
Tags
Notes
The answer RADIUMS is so rare that it appears less than once every 2500 puzzles.
Definition
RADIUM as a noun:
1. (radium, Ra, atomic number 88) = an intensely radioactive metallic element that occurs in minute amounts in uranium ores