What is a poisonous alkaloid, C19H21NO3, found in opium in small quantities, having a sharp, astringent taste, and a tetanic action resembling that of strychnine called?

thebaine — A poisonous alkaloid, C19H21NO3, found in opium in small quantities, having a sharp, astringent taste, and a tetanic action resembling that of strychnine. (Webster's 1913.)

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