How to say "ad-lib" in Japanese

• アドリブCommon
  no-adjectiveThe direct loanword and safest default: remarks or lines made up on the spot rather than scripted, as when a comedian or presenter departs from prepared material. In music it also covers improvised solos.
• 即席そくせきCommon
  no-adjectiveImpromptu in the sense of something thrown together on the spot without preparation, as an impromptu speech. It stresses the hasty, improvised character of the thing rather than the act of improvising in performance.
  彼かれは即席そくせきに立派りっぱな演説えんぜつをした。↗

  He made a splendid off-the-cuff speech.
• フェイクCommon
  nounA music word: improvised vocal runs or riffs in jazz and similar singing — the sense of ad-libbing in song. For spoken ad-libs it is not the word you want.
• 即興そっきょうCommon
  no-adjectiveImprovisation itself: performing or creating something on the spot without a script or rehearsal, as in impromptu comedy or music. The natural choice when 'ad-lib' means the act of improvising.

Use 「アドリブ」 for spoken ad-libs, 「フェイク」 for improvised vocal runs in jazz and pop singing, 即興 for improvisation as an act or performance, and 即席 for anything impromptu or thrown together on the spot.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• アドリブad lib
• 即席そくせきimpromptu
• 即興的そっきょうてきimprovised
• フェイクimprovisation (in jazz music, singing, etc.)
• 即興そっきょうimprovised