noun
The act of creating or performing something spontaneously without preparation, especially in music, theater, or speech.
彼のピアノ演奏は完全な即興だった。
His piano performance was complete improvisation.
noun which may take the genitive case particle 'no'
Describes something done or made on the spot without planning; often used as a prenominal modifier (即興の〜).
即興のスピーチを頼まれた。
I was asked to give an impromptu speech.