the opening prayer of that service, declaring null in advance any purely religious vows one may come to make in the coming year
Word origin
Aramaic kōl nidhrē all the vows; the prayer's opening words
Kol Nidre in American English
(koʊl ˈnidreɪ; ˈnɪdrə; Hebrew ˈkɔlniˈdʀeɪ)
1.
the prayer declaring a release from religious vows and obligations that were made unintentionally or under duress: it is recited in synagogues at the opening of Yom Kippur eve services
2.
the traditional music to which this is sung
Word origin
Heb-Aram kol-nidre, all (our) vows: opening words of prayer < Aram kol, all + nidre, vows, pl. of neder, vow < root ndr, to vow