SENATE, SENATOR (זָקֵנ֮, H2418, elder, aged, senior; γερουσία, G1172, assembly of elders). The term “senate” in Eng. came from the Lat. senatus, meaning an assembly of elders (from senex, an old man). Among the Romans the State Council, or Senate, was most ancient—from before the expulsion of the Tarquins; it consisted of 100 men. Later the number was increased to 300, and plebeians were made eligible as well as patricians. Under the Empire, the number was increased to 900 by Julius Caesar but was reduced to 600 by Augustus, who added age and property requirements. Under the Empire, the principal duties of the Senate consisted of (1) the maintenance of state religion, (2) supervision of government property and finances, (3) control of the senatorial provinces, (4) legislative ratification of the emperor’s decisions, (5) jurisdiction over breach of contract, cases of high treason, and offenses of senators, and (6) exercise of the right to nominate all magistrates except consuls.
In the OT, the chief magistrates of Israel are called “senators” in the KJV (Ps 105:22). The word זָקֵנ֮, H2418, is elsewhere rendered “elder,” and is consistently rendered “elder” in the RSV.
In the NT, the term γερουσία, G1172, is tr. “senate,” even in the RSV (Acts 5:21). It seems to have represented a more inclusive body than just the Sanhedrin, for the reference speaks of the high priest having called together “the council, and all the senate of Israel.” Perhaps these were additional elders who did not sit in the council. On the other hand, the Gr. could be rendered “called together the council, even all the senate of Israel,” in which instance the Sanhedrin and the Senate would be the same. Such a statement would be a redundancy due perhaps to Luke’s consciously Septuagintal style.