The Collaborative International Dictionary of English v.0.48:

Vagus \Va"gus\, a. [L., wandering.] (Anat.)
   Wandering; -- applied especially to the pneumogastric nerve.
   -- n. The vagus, or pneumogastric, nerve.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vagus
    n 1: a mixed nerve that supplies the pharynx and larynx and
         lungs and heart and esophagus and stomach and most of the
         abdominal viscera [syn: vagus, vagus nerve, nervus
         vagus, pneumogastric, pneumogastric nerve, tenth
         cranial nerve, wandering nerve]