actinium series

15 LETTERS · STARTS WITH A

actinium series is a valid 15-letter word worth 18 points in Scrabble and 22 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

A1C3T1I1N1I1U1M3S1E1R1I1E1S1

1 + 3 + 1 + 1 + 1 + 1 + 1 + 3 + 0 + 1 + 1 + 1 + 1 + 1 + 1 =18 PTS

DOUBLE WORD → 36TRIPLE WORD → 54

MEANING

What does actinium series mean?