axon
n. the long, thin, hollow, cylindrical extension of a neuron that normally carries a nerve impulse away from the cell body. An axon often branches extensively and may be surrounded by a protective myelin sheath. Each branch of an axon ends in a terminal button (also called synaptic bouton or knob, among numerous other synonyms) from which an impulse is transmitted, through discharge of a neurotransmitter, across a synapse to a neighboring neuron. Also called nerve fiber. —axonal
adj.