radioactive isotope

19 LETTERS · STARTS WITH R

radioactive isotope is a valid 19-letter word worth 26 points in Scrabble and 29 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

R1A1D2I1O1A1C3T1I1V4E1I1S1O1T1O1P3E1

1 + 1 + 2 + 1 + 1 + 1 + 3 + 1 + 1 + 4 + 1 + 0 + 1 + 1 + 1 + 1 + 1 + 3 + 1 =26 PTS

DOUBLE WORD → 52TRIPLE WORD → 78

MEANING

What does radioactive isotope mean?