extension bit

13 LETTERS · STARTS WITH E

extension bit is a valid 13-letter word worth 21 points in Scrabble and 24 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

E1X8T1E1N1S1I1O1N1B3I1T1

1 + 8 + 1 + 1 + 1 + 1 + 1 + 1 + 1 + 0 + 3 + 1 + 1 =21 PTS

DOUBLE WORD → 42TRIPLE WORD → 63

MEANING

What does extension bit mean?