decemvir
noun
de·cem·vir di-ˈsem-vər 
: one of a ruling body of 10
specifically : one of a body of 10 magistrates in ancient Rome
decemviral
di-ˈsem-vər-əl
adjective decemvirate
di-ˈsem-vər-ət
noun 
Word History
Etymology
Middle English, from Latin, back-formation from decemviri, plural, from decem + viri, plural of vir man — more at virile
First Known Use
15th century, in the meaning defined above