slack filling

13 LETTERS · STARTS WITH S

slack filling is a valid 13-letter word worth 22 points in Scrabble and 28 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

S1L1A1C3K5F4I1L1L1I1N1G2

1 + 1 + 1 + 3 + 5 + 0 + 4 + 1 + 1 + 1 + 1 + 1 + 2 =22 PTS

DOUBLE WORD → 44TRIPLE WORD → 66

MEANING

What does slack filling mean?