Quick Definition
γερουσία, ας, ἡ n.f. body of elders
Strong's Definition
from 1088; the eldership, i.e. (collectively) the Jewish Sanhedrin
KJV Usage: senate
UBS Dictionary of the Greek New Testament
noun, f. | -ας | γηράσκω
11.83 · Groups and Classes of Persons and Members of Such Groups and Classes · Socio-Political
Sanhedrin, high council of the Jews the highest council of the Jews (see also συνέδριον[b] ‘Sanhedrin,’ the council of the Jews, 11.80) but with the implication of the maturity and relative advanced age of those constituting the membership of such a council
1 Though γερουσία and πρεσβυτέριον[a] refer to the same council of the Jews as the term συνέδριον[b] (11.80), this does not mean that the three terms are completely identical in meaning. The focus upon maturity of age and judgment as well as presumed social standing are more significant factors in γερουσία and πρεσβυτέριον[a] than in συνέδριον[b].
UBS Dictionary of the Greek New Testament © United Bible Societies, licensed CC BY-SA 4.0.
Thayer's Greek Lexicon
γερουσία, -as, 7, (adj. γερούσιος, belonging to old men, γέρων), a senate, council of elders; used in prof. auth. of the chief council of nations and cities (ἐν ταῖς πόλεσι ai yepovoia, Xen. mem. 4, 4, 16; in the O. T. of the chief council not only of the whole people of Israel, Ex. iii. 16, ete.; 1 Mace. xii. 6, ete. ; but also of cities, Deut. xix. 12, ete.) ; of the Great Council, the Sanhedrin of the Jews: Acts v. 21, where to τὸ συνέδριον is added καὶ πᾶσαν τὴν γερουσίαν τῶν υἱῶν Ἰσραήλ and indeed (καί explicative) all the senate, to signify the full Sanhedrin. [Cf. Schiirer, Die Gemeindeverfassung d. Juden in Rom in ἃ. Kaiserzeit nach ἃ. Inschriften dargestellt. Leips. 1879, p. 18 sq.; Hatch, Bamp. Lects. for 1880, p. 64 sq.]
Mounce Concise Greek Dictionary
γερουσία gerousia 1x
a senate, assembly of elders; the elders of Israel collectively, Acts 5:21*
Abbott-Smith Greek Lexicon
γερουσία, -ας, ἡ
(< γέρων), [in LXX (Hex. only in OT) for זָקֵן;]
a council of elders, senate; in NT, of the Sanhedrin (Cl. Rev., i, 43 f.; DB, ext., 99): Ac 5:21.†
Liddell-Scott-Jones — Greek-English Lexicon
γερουσία (gerousia) — council of elders. γερουσί-α, ἡ, Council of Elders, senate, [Refs 5th c.BC+]; compare γερωΐα and γεροντί; also of the Carthaginian [Refs 4th c.BC+]; and the Roman, [Refs 1st c.AD+]; of the Jewish Sanhedrin, [LXX+NT]
2. sacred college, ἱερὰ γ. [Refs 3rd c.BC+]
II. ={πρεσβεία}, [Refs 5th c.BC+]