principal series

16 LETTERS · STARTS WITH P

principal series is a valid 16-letter word worth 21 points in Scrabble and 26 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

P3R1I1N1C3I1P3A1L1S1E1R1I1E1S1

3 + 1 + 1 + 1 + 3 + 1 + 3 + 1 + 1 + 0 + 1 + 1 + 1 + 1 + 1 + 1 =21 PTS

DOUBLE WORD → 42TRIPLE WORD → 63

MEANING

What does principal series mean?