WordNet (r) 3.0 (2006):

Pythias
    n 1: friend of Damon; Phintias (according to legend) was
         condemned to death by Dionysius the Elder and asked a
         respite to put his affairs in order; Damon pledged his life
         for the return of his friend; when Phintias returned in
         time the tyrant released them both (4th century BC) [syn:
         Phintias, Pythias]