SENATE (Gr. gerousia, a council of elders). Mentioned in Acts.5.21, in KJV, RSV, NEB (niv “assembly of the elders”); not a body different from the “council” (Sanhedrin), but a more precise designation indicating its dignity as composed of old men.
SENATE, SENATOR (זָקֵן, 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 זָקֵן, 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.
International Standard Bible Encyclopedia (1915)
sen’-at, sen’-a-ter: In Ps 105:22, "teach his senators (the (British and American) "elders") wisdom." The Hebrew is zaqen, "elder" Septuagint presbuteroi). In Ac 5:21, "called the council together and all the senate of the children of Israel." The Greek gerousia, is here evidently used as a more precise equivalent of the foregoing "council" (sunedrion), to which it is added by kai, explicative. Reference is had to the Sanhedrin. See Sanhedrin. This term gerousia occurs in Septuagint Ex 3:16, etc., and in 1 Macc 12:6; 2 Macc 1:10; 4:44 of the supreme council of the Jews (see Government). In 1 Macc 8:15; 12:3, bouleuterion, is used of the Roman senate, which is said to consist of 320 members meeting daily, consulting always for the people, to the end that they may be well governed. These statements are not quite accurate, since the senate consisted normally of 300 members, and met not daily, but on call of the magistrates. Originally, like the gerousia of the Jews, the representatives of families and clans (gentes), the senators were subsequently the ex-magistrates, supplemented, to complete the tale of members, by representatives of patrician (in time also of plebeian) families selected by the censor. The tenure was ordinarily for life, though it might be terminated for cause by the censor. Although constitutionally the senate was only an advisory body, its advice (senatus consultum, auctoritas) in fact became in time a mandate which few dared to disregard. During the republican period the senate practically ruled Rome; under the empire it tended more and more to become the creature and subservient tool of the emperors.