labial vein

NOUN
11 LETTERS · STARTS WITH L

labial vein is a valid 11-letter word worth 15 points in Scrabble and 20 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
L1A1B3I1A1L1V4E1I1N1
1 + 1 + 3 + 1 + 1 + 1 + 0 + 4 + 1 + 1 + 1 =15 PTS
DOUBLE WORD → 30TRIPLE WORD → 45
MEANING

What does labial vein mean?