The Collaborative International Dictionary of English v.0.48:

Septemvir \Sep*tem"vir\, n.; pl. E. Septemvirs, L.
   Septemviri. [L. septemviri, pl.; septem seven + viri, pl.
   of vir man.] (Rom. Hist.)
   One of a board of seven men associated in some office.
   [1913 Webster]