נִידּוּי, (נָדָה) banishment, isolation. Num. R. s. 10 תהא בנ׳ (Sabb. 64ᵇ, a. e. בנדתה), v. נִדָּה.—Esp. excommunication, of a higher degree than נְזִיפָה and lesser than חֵרֶם. M. Kat. 16ᵃ אין נ׳ פחות וכ׳ nidduy lasts no less than thirty days. Ib. נִידּוּיוֹ נ׳ the excommunication pronounced by him is valid. Ber. 19ᵃ גוזרני עליך נ׳ I should have decreed the ban over; a. fr.