liquid unit

NOUN
11 LETTERS · STARTS WITH L

liquid unit is a valid 11-letter word worth 20 points in Scrabble and 24 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
L1I1Q10U1I1D2U1N1I1T1
1 + 1 + 10 + 1 + 1 + 2 + 0 + 1 + 1 + 1 + 1 =20 PTS
DOUBLE WORD → 40TRIPLE WORD → 60
MEANING

What does liquid unit mean?