Definition of "impromptu" in English

adjective

1. Improvised; without prior preparation, planning or rehearsal.

   • The party began with an impromptu rendition of 'Happy Birthday'.
   • an impromptu speech

noun

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

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