meaning of impromptu
1. Offhand; without previous study; extemporaneous; extempore; as, an impromptu verse.
2. Something made or done offhand, at the moment, or without previous study; an extemporaneous composition, address, or remark.
3. A piece composed or played at first thought; a composition in the style of an extempore piece.
4. an extemporaneous speech or remark; "a witty impromptu must not sound
">premeditated"