[im.promp.tu] n [F, fr. impromptu extemporaneously, fr. L in promptu in readiness] (1683) 1: something that is impromptu
2: a musical composition suggesting improvisation
[2]impromptu adj (1764) 1: made, done, or formed on or as if on the spur of the moment: improvised
2: composed or uttered without previous preparation: extemporaneous -- impromptu adv