incontestable clause

20 LETTERS · STARTS WITH I

incontestable clause is a valid 20-letter word worth 25 points in Scrabble and 33 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

I1N1C3O1N1T1E1S1T1A1B3L1E1C3L1A1U1S1E1

1 + 1 + 3 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 0 + 3 + 1 + 1 + 1 + 1 + 1 =25 PTS

DOUBLE WORD → 50TRIPLE WORD → 75

MEANING

What does incontestable clause mean?