jí​xìng

impromptu

即兴 (即興) jí​xìng
impromptu adverb
done or spoken without preparation; extemporaneous

His impromptu speech won rounds of applause.

improvisation adjective
the creative process or result of performing without a script or score, especially in the arts

The essence of jazz lies in improvisation.

Frequency

Movie subtitles
4.83 per million appears in 2% of films
Written text
2.52 per million

Sources

Definitions
CC-CEDICT