The Collaborative International Dictionary of English v.0.48:

Centumvir \Cen*tum"vir\, n.; pl. Centumviri. [L., fr. centum
   hundred + Vir man.] (Rom. Hist.)
   One of a court of about one hundred judges chosen to try
   civil suits. Under the empire the court was increased to 180,
   and met usually in four sections.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

CENTUMVIRI, civil law. the citizens of Rome were distributed into thirty-
five tribes, and three persons out of each tribe were elected judges, who
were called centumviri, although they were one hundred and five in number.
They were distributed into four different tribunals, but in certain causes
called centumvirales causas, the judgments of the four tribunals were
necessary. Vicat,.ad verb.; 3 Bl. Com. 315.