a provocative song-dance sequence in a movie (often completely un-connected with the main story).  Classic item numbers performed by mainstream leading ladies made their first appearance in the early 1990s.   Madhuri Dixit took this to the next level with Choli Ke Peechey Kya Hai? in the 1993 movie Khalnayak.  Provocative lyrics and dance moves by the star performer caused a stir but the song and the movie climbed to the top of the charts. Since then, Item Numbers have become very much mainstream in Indian movies, here is Dilbar from 2018    and Chamma Chamma from 2019

See also cabaret.