comma blunder

13 LETTERS · STARTS WITH C

comma blunder is a valid 13-letter word worth 21 points in Scrabble and 28 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

C3O1M3M3A1B3L1U1N1D2E1R1

3 + 1 + 3 + 3 + 1 + 0 + 3 + 1 + 1 + 1 + 2 + 1 + 1 =21 PTS

DOUBLE WORD → 42TRIPLE WORD → 63

MEANING

What does comma blunder mean?