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neurotransmitter neu·ro·trans·mit·ter (nur'ō-trāns'mĭt-ər, -trānz'-, nyur'-)
Any of the various chemical substances, such as acetylcholine, that transmit nerve impulses across a synapse.
Any one of a number of chemicals that are used to transmit nerve signals across a synapse. They are sprayed from the end of the “upstream” nerve cell and absorbed by receptors in the “downstream” cell.
Note: Drugs like Prozac and alcohol affect the emission and reception of neurotransmitters.