vagus (VAY-guhs) pl. vagi (VAY-gee) - n., either of the two tenth cranial nerves.
So, there's thirteen pairs of nerves that leave the cranium itself, rather than the spine, the tenth of which (by some spatial ordering system) is the vagus nerves. The name, in case you're wondering, comes from Latin for wandering: it's the longest nerve of the autonomic nervous system, controlling (and conducting sensory information from) the pharynx, larynx, heart, and all the abdominal organs above the latter half of the colon except the adrenal glands (including the uterus). I'd include a picture, but frankly I'm not readily finding anatomical diagrams that include just a vagus and all of it. So I'll just have to leave you with the tidbit that it's worth 12 points in Words With Friends and 9 points in Scrabble.