The Collaborative International Dictionary of English v.0.48:

Quindecemvir \Quin`de*cem"vir\, n.; pl. E. Quindecemvirs, L.
   Quindecemviri. [L., from quindecim fifteen + vir a man.]
   (Rom. Antiq.)
   One of a sacerdotal college of fifteen men whose chief duty
   was to take care of the Sibylline books.
   [1913 Webster]