The term Niggun Devekut, which probably is a Hebrew translation of the Yiddish expression "A dveykes nign" or "A Dveyke", and is found in contemporary sources and among Hebrew speaking Hassidim, literally refers to meditational tunes which "function as means to help the Hassid enter into a meditative state of union with God." These niggunim are characterized by slow tempi expressing serious, meditational, supplicatory or even sad feelings. They appear in various meters, and some of them have unstable time organization, e.g. mixing non-metric, recitational with metric phrases, variability of tempo, rubato fluctuations, etc. Tunes of this type appear, in different sources and interviews, as a means of achieving spiritual elevation (hit'alut), soul searching (heshbon ha-nefesh), repentance (teshuvah), and more, and among the Slonim hassidim as a technique of praising God and "talking" to him.
This term is not used in all communities. Several alternatives exist. Hassidim from Toldot Aharon and other communities use the Hebrew term "niggun hit'orerut" ("awakening tune"), while members of the Spinka dynasty in Jerusalem speak about "niggun rigshi" ("an emotional tune"). Other Hassidim from Jerusalem employ the Yiddish terms "beyt nign" ("a begging tune"), "harts nign" ("a tune from the heart") and moralishe niggunim. The last term is also used in the Modzhitz community in Israel. The Lubavitcher Hassidim use several terms, such as "niggun ga'agu'im" ("longing tune") and "volakh" or "volekhl" (from Walachia in Rumania), to indicate niggunim of a similar style. However, among the Lubavitcher "niggunei hitva'adut" ("gathering tunes"), Sabbath and Holidays niggunim, and tunes denominated by various titles, one can find many tunes of that similar style.
These tunes, whether with or without text, are considered the core of musical creativity in all hassidic communities. They are mostly performed at the Hassidic tish (festive meals in presence of the rebbe occurring on Sabbaths and holidays; see: Admor & tish), and therefore they are sometimes called tish niggunim (lit. "table tunes"). The Hassidic communities ascribe an aura of holiness to those tunes that are sung to texts holding mystical connotations, such as the Kabbalistic Sabbath piyyut Benei heikhala by Isaac Luria Ashkenazi and the Hassidic piyyut Yah ekhsof by Aharon of Karlin,, as well as other piyyutim and prayers such as Yah Ribbon by Israel Najara (see third sound example), the Passover piyyut Brah dodi and the prayer Heye im pifiyot from the mussaf service of the Day of Atonement. Some of these tunes serve to emotionally prepare the bride and groom for the wedding ceremony (kiddushin), while other tunes are sung when the groom is lead to the Badekns ceremony, to the wedding canopy (huppa), or awaits the bride under the canopy, when the bride is led to the canopy and when the groom encircles the bride under the canopy.
 Vinaver-Schleifer, Anthology of Hassidic music, p. 191. In reference to this term among Ashkenazic hazzanim, see: Avenary, The musical vocabulatory of the Ashkenazic Hazanim, p. 190.
 See examples in Zalmanov, Sefer hanigunim, nos. 8, 9, 31, 307-309; Geshuri, Haniggun Veharikud Bahassidut, part 1, pp. 41-42, Nos. 2-3, and p. 60, no. 9.
 Yaakov Mazor, Koho Shel Haniggun Bahagut Hahassidit Vetafkidav Bahavay Hadati Vehahevrati, pp. 41-42, 45-46.
 For examples see Zalmanov, nos. 60, 131-138, 203-204, 302-306; Mazor-Hajdu, Niggunei Simha Verikud shel Hahassidim, side 2, band 2; for the use of volakh by Ashkenazic hazzanim see Avenary, ibid, p. 195.
 For examples see Zalmanov, nos. 1, 6, 22, 44, 74, 84, 119, 122, 271, 273, 276, 277.
 See in Vinaver-Schleifer, Anthology of Hassidic music, Nos. 39 and 41.
 Yaakov Mazor, Mekoma Shel Hamusika Bahatuna Hahassidit, pp. 75-77, no. 2 and p. 78, no. 3; Hajdu-Mazor, The Musical Tradition of Hasidism,pp. 432-3, ex. 6.