backing paper

13 LETTERS · STARTS WITH B

backing paper is a valid 13-letter word worth 25 points in Scrabble and 31 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

B3A1C3K5I1N1G2P3A1P3E1R1

3 + 1 + 3 + 5 + 1 + 1 + 2 + 0 + 3 + 1 + 3 + 1 + 1 =25 PTS

DOUBLE WORD → 50TRIPLE WORD → 75

MEANING

What does backing paper mean?