log z's

VERB
7 LETTERS · STARTS WITH L

log z's is a valid 7-letter word worth 15 points in Scrabble and 17 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
L1O1G2Z10'0S1
1 + 1 + 2 + 0 + 10 + 0 + 1 =15 PTS
DOUBLE WORD → 30TRIPLE WORD → 45
MEANING

What does log z's mean?