A short recurring passage, particularly the tutti section of a Baroque aria or concerto movement. Most of the recurring instrumental sections in Monteverdi's operas are entitled ‘ritornello’ and the term was similarly used in England, Germany and France, where the ritournelle, usually in triple time, came to signify a section to be danced after a song.
By the 18th century a typical form of the ritornello aria was: ritornello in the tonic key; first solo, moving to the dominant or relative major; shortened ritornello in the new key, second solo, modulating and cadencing in the tonic; full ritornello in the tonic (sometimes with solo interruptions). In a da capo aria this pattern was repeated after a central section. The same basic design, extended to cover more key centres, was used for fast movements in Baroque concertos (Vivaldi, Bach etc); and combined with sonata-form elements it reached a new level of complexity in Mozart's piano concertos.