endorsement in blank

NOUN
20 LETTERS · STARTS WITH E

endorsement in blank is a valid 20-letter word worth 27 points in Scrabble and 34 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
E1N1D2O1R1S1E1M3E1N1T1I1N1B3L1A1N1K5
1 + 1 + 2 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 0 + 1 + 1 + 0 + 3 + 1 + 1 + 1 + 5 =27 PTS
DOUBLE WORD → 54TRIPLE WORD → 81
MEANING

What does endorsement in blank mean?

NOUN · 1 SENSE
1

An endorsement on commercial paper naming no payee and so payable to the bearer.