Coniine is a toxic alkaloid that is naturally present in a number of plants, including hemlock and poison hemlock. This compound has been identified as the primary active ingredient responsible for the poisonous effects of these plants, which can cause convulsions, paralysis, respiratory failure, and even death in humans and animals. There are several synonyms for coniine, including piperidine, ethyl piperidine, and methyl piperidine. These compounds are structurally similar to coniine and may have similar effects on the body. However, they are not as toxic as coniine and are not typically found in significant quantities in hemlock or other plants.