neuron (n.)

before vowels neur-, word-forming element meaning "pertaining to a nerve or nerves or the nervous system," from Greek neura "nerve" (Galen), originally "sinew, bowstring," also neuron "sinew, string (of a bow or musical instrument); cord; penis;" in plural "strength, vigor," from PIE *(s)neuro- "tendon, sinew" (see nerve (n.)). In Greek, puppets were neurospastos, literally "drawn by strings."

1939, from neuron + first element from internuncial (adj.) "communicating between different parts of the body," from Latin internuncius "a messenger, mediator," from inter "between" (see inter-) + nuntius "messenger" (from PIE root *neu- "to shout").