impromptu

 
Pronunciation: /ɪmˈprɒm(p)tjuː/

adjective & adverb

  • done without being planned or rehearsed: [as adjective]: an impromptu press conference [as adverb]: he spoke impromptu

noun (plural impromptus)

  • a short piece of instrumental music, especially a solo, that is reminiscent of an improvisation.

Origin:

mid 17th century (as an adverb): from French, from Latin in promptu 'in readiness', from promptus (see prompt)