"A drug with properties and effects similar to a known
hallucinogen or narcotic but having a slightly altered chemical structure, especially such a drug created in order to evade restrictions against illegal substances."
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Answers.com)
A synthetic chemical (Often produced by a high-tech lab) the purpose of which is to produce a reliable state of intoxication (As opposed to
plant-based inebrients, whos effects may vary greatly from one individual to another)