What does the word impromptu mean?

Usage examples for impromptu

  1. What you formerly enquired of me in the streets, I beg you now to come and ask me at my house, when you shall see that the questions to which I before replied, impromptu, shall be more perfectly answered now that I shall take time to consider." – The Exemplary Novels of Cervantes by Miguel de Cervantes Saavedra
  2. I explained that they consisted mainly of " notes" for future use, but consented willingly; whereupon he arranged a number of them as for exhibition and delivered himself impromptu of the most vehemently instructive lecture on art I had ever heard. – The Guest of Quesnay by Booth Tarkington