intoxicant
n. a substance capable of producing transient alterations in mental function. The nature of the intoxication depends on the psychoactive properties of the intoxicant. In general, mild intoxication is marked by minor perceptual changes or a sense of euphoria or well-being; more pronounced intoxication involves such changes as behavioral disinhibition, perceptual distortions, hallucinations, or delirium; and severe intoxication is marked by loss of motor control and cognitive and autonomic function, possibly progressing to coma or death.