impromptu

/ษชmหˆpษนษ’mptju/

IPA: /IH0 M P R AA1 M P T UW0/

noun
  1. 1

    A short musical composition for an informal occasion often with the character of improvisation and usually to be played solo.

  2. 2

    (by extension) Any composition, musical or otherwise, that is created on the spot without preparation.

adjective
  1. 1

    Improvised; without prior preparation, planning or rehearsal.

    โ€œThe party began with an impromptu rendition of 'Happy Birthday'.โ€

Source: https://en.wiktionary.org/wiki/impromptu