Jastrow: עֲצֶרֶת

עֲצֶרֶת f. (b. h.; עָצַר) detention, gathering, esp. a festive gathering for the conclusion of a festive season, concluding feast; ע׳ של חג the concluding feast of the Succoth festival (Num. XXIX, 35); ע׳ של פסח the concluding feast of the Passover festival i.e. the Feast of Weeks, Pentecost. Pesik. Bayom, p. 193ᵃ ראויה היתה ע׳ של חג … כשם שע׳ של פסח וכ׳ by right the concluding feast of the Succoth Festival was to have been fifty days after (the first day of Succoth) as the concluding feast of Passover is &c.; Cant. R. to VII, 2; a. e.—In gen. ע׳ f., (sub. יום) m. Feast of Weeks, Pentecost. Pesik. l. c., p. 190ᵇ בסיון ע׳ in the month of Sivan is the Feast of Weeks. Ḥag. II, 4 ע׳ שחל להיות וכ׳ if the Feast of Weeks occurs on a Friday. Ib. שלא לקיים … ע׳ אחר השבת to oppose those who say that the Feast of Weeks must be observed on the day after the Sabbath (after seven complete weeks from Passover, beginning with the first Sunday); Men. 65ᵃ. Ib. 65ᵇ; a. v. fr.