minor tranquillizer

NOUN
19 LETTERS · STARTS WITH M

minor tranquillizer is a valid 19-letter word worth 38 points in Scrabble and 44 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
M3I1N1O1R1T1R1A1N1Q10U1I1L1L1I1Z10E1R1
3 + 1 + 1 + 1 + 1 + 0 + 1 + 1 + 1 + 1 + 10 + 1 + 1 + 1 + 1 + 1 + 10 + 1 + 1 =38 PTS
DOUBLE WORD → 76TRIPLE WORD → 114
MEANING

What does minor tranquillizer mean?