minor tranquilizer

NOUN
18 LETTERS · STARTS WITH M

minor tranquilizer is a valid 18-letter word worth 37 points in Scrabble and 42 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
M3I1N1O1R1T1R1A1N1Q10U1I1L1I1Z10E1R1
3 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 1 + 10 + 1 + 1 + 1 + 1 + 10 + 1 + 1 =37 PTS
DOUBLE WORD → 74TRIPLE WORD → 111
MEANING

What does minor tranquilizer mean?