impromptu

Adjective

• with little or no preparation or forethought
  • his ad-lib comments showed poor judgment
    
  • an extemporaneous piano recital
    
  • an extemporary lecture
    
  • an extempore skit
    
  • an impromptu speech
    
  • offhand excuses
    
  • trying to sound offhanded and reassuring
    
  • an off-the-cuff toast
    
  • a few unrehearsed comments
    

Adverb

• without advance preparation
  • he spoke ad lib
    

Noun

• a short musical passage that seems to have been made spontaneously without advance preparation

• an extemporaneous speech or remark
  • a witty impromptu must not sound premeditated
    

Related words

• Synonyms: 
  ad-lib , extemporaneous , extemporary , extempore , offhand , offhanded , off-the-cuff , unrehearsed , ad lib , ad libitum , spontaneously