Noun | 1. | neurotransmitter - a neurochemical that transmits nerve impulses across a synapse Adrenalin, adrenaline, epinephrin, epinephrine - a catecholamine secreted by the adrenal medulla in response to stress (trade name Adrenalin); stimulates autonomic nerve action GABA, gamma aminobutyric acid - an amino acid that is found in the central nervous system; acts as an inhibitory neurotransmitter neurochemical - any organic substance that occurs in neural activity acetylcholine - a neurotransmitter that is a derivative of choline; released at the ends of nerve fibers in the somatic and parasympathetic nervous systems |