Definitions

1. adjective

done or given without prior planning or preparation; spontaneous

“She performed an impromptu dance in the living room.”

2. noun

an unprepared or spontaneous performance or speech

“The comedian’s impromptu joke about the audience’s country of origin was hilarious.”

3. noun

something done or given without prior planning or preparation

“The impromptu speech by the student was warmly received by the audience.”