hallucinogen

NOUN /hə'lusənə,dʒɛn/
12 LETTERS · 5 SYLLABLES · STARTS WITH H

hallucinogen is a valid 12-letter word worth 18 points in Scrabble and 24 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
H4A1L1L1U1C3I1N1O1G2E1N1
4 + 1 + 1 + 1 + 1 + 3 + 1 + 1 + 1 + 2 + 1 + 1 =18 PTS
DOUBLE WORD → 36TRIPLE WORD → 54
MEANING

What does hallucinogen mean?