Coniine is a toxic alkaloid primarily found in the plant poison hemlock (Conium maculatum). It is a colorless, oily liquid that can be harmful if ingested, affecting the nervous system and potentially leading to respiratory failure. Historically, it is known for its role in the death of the philosopher Socrates, who was sentenced to drink a poison containing coniine. The compound works by blocking the action of the neurotransmitter acetylcholine at nerve endings, which disrupts normal muscle function. Due to its toxicity, coniine is not used in medicine and is considered a dangerous substance.