impromptu：释义

Prompted by the occasion rather than being planned in advance: an impromptu party.

Spoken, performed, done, or composed with little or no preparation; extemporaneous: a few impromptu remarks. See Synonyms at extemporaneous.

With little or no preparation; extemporaneously.

Something, such as a speech, that is made or done extemporaneously.

Music A short composition, especially for the piano, performed in an offhand or extemporized style.