עֲצָרָה `atserah "assembly" usually a religious "assembly" (Am 5:21), seems at times a technical term for the last day of a festival season (especially the feast of booths/tabernacles: Lev 23:36; Num 29:35; Neh 8:18; 2 Chron 7:9), in Joel it suggests a day of fasting and prayer in the context of Adonai's Day (Joel 1:14; 2:15).