decurion

noun

de·​cu·​ri·​on di-ˈkyu̇r-ē-ən 

1

: a Roman cavalry officer in command of 10 men

2

: a member of a Roman senate

Word History

Etymology

Middle English decurioun, from Latin decurion-, decurio, from decuria division of ten, from decem

First Known Use

14th century, in the meaning defined at sense 1