ri·tor·nel·lo 
(rē′tôr-nĕllō)
(rē′tôr-nĕllō)n. pl. ri·tor·nel·li (-lē) or ri·tor·nel·los
1. An instrumental interlude recurring after each stanza in a vocal work.
2. A passage or section for full orchestra in a concerto or aria.
3. An instrumental interlude in early 17th-century opera.
4. The refrain of a rondo.
[Italian, diminutive of ritorno, return, from ritornare, to return, from Vulgar Latin *retornāre; see RETURN.]