A nigun ( meaning "tune" or "melody", pl. nigunim) or niggun (pl. niggunim) is a form of Jewish religious song or tune sung by groups. It is vocal music, often with repetitive sounds such as "bim-bim-bam" or "ai-ai-ai!" instead of formal lyrics. Sometimes, Bible verses or quotes from other classical Jewish texts are sung repetitively to form a nigun. Some nigunim are sung as prayers of lament, while others may be joyous or victorious.
Nigunim are largely improvisations, though they could be based on thematic passage and are stylized in form, reflecting the teachings and charisma of the spiritual leadership of the congregation or its religious movement. Nigunim are especially central to worship in Hasidic Judaism, which evolved its own structured, soulful forms to reflect the mystical joy of intense prayer ( devekut).