Servi

SERVI. This name was given by the Romans to their slaves; they were so called from servare, to preserve, from the ancient practice of the generals of the army, who were accustomed to sell their captives, and preserved them rather than kill them: servi autem ex eo appellati sunt, quod imperatores captivos vendere, ac per hoc servare, nec occidere solent. Inst. 1 3, 3.