Or matsereth {ats-eh'-reth}; from atsar; an assembly, especially on a festival or holiday -- (solemn) assembly (meeting).
see HEBREW atsar
H6116. atsarah
or atsereth עֲצֶ֫רֶת עֲצָרָה, noun feminine assembly (? as confined, held in); — absolute עֲצָרָה Isaiah 1:13 2t.; עֲצֶ֫רֶת Deuteronomy 16:8 3t., עֲצָ֑רֶת2 Chronicles 7:9; construct עֲצֶ֑רֶת Jeremiah 9:1; plural suffix עַצְרֹתֵיכֶם Amos 5:21; —
1 sacred assembly, rejected by ׳י, Isaiah 1:13 and (at Bethel, etc.) Amos 5:21; for Baal 2 Kings 10:20; Deuteronomy 16:8 (last day of Maƒƒoth), Leviticus 23:36 (P), Numbers 29:35 (P), Nehemiah 8:18 (all of day after feast of booths), compare 2 Chronicles 7:9 [Late Hebrew of feast of weeks, עֲצַרְתָּא ᵑ7 JosAnt. iii. 10, 6 Ἀσάρτα]; occasional, Joel 1:14; 2:15.
2 assemblage, company (in General), ׳ע בֹּגְדִים Jeremiah 9:1 an assemblage of deceivers (Gr עֲדַת; Che חֶבְרַת).