› to invent or make something, such as a speech or a device, at the time when it is needed without already having planned it: I hadn't prepared a speech so I suddenly had to improvise. To sleep on, we improvised a mattress from a pile of blankets.Inventing, designing and innovationCreating and producing › When actors or musicians improvise, they perform without prepared speech or music, making up the play, music, etc. as they perform it: During certain scenes of the play there isn't any script and the actors just improvise (the dialogue).Acting, rehearsing and performingPlaying musicSinging in general