The Collaborative International Dictionary of English v.0.48:

Intoxicant \In*tox"i*cant\, n.
   That which intoxicates; an intoxicating agent; as, alcohol,
   opium, and laughing gas are intoxicants.
   [1913 Webster]

WordNet (r) 3.0 (2006):

intoxicant
    adj 1: causing [syn: intoxicant, intoxicating]
    n 1: a liquor or brew containing alcohol as the active agent;
         "alcohol (or drink) ruined him" [syn: alcohol, alcoholic
         drink, alcoholic beverage, intoxicant, inebriant]
    2: a drug that can produce a state of intoxication