The term you are looking for is "ritornello." In music, a ritornello is a recurring section that typically alternates with contrasting episodes and is often found in Baroque concertos and other forms. The other terms you mentioned refer to different concepts:
- "Gigue" is a lively dance form.
- "Terrace" often refers to dynamics changing suddenly without gradual crescendos or decrescendos.
- "Ripieno" refers to the full orchestra in a concerto grosso, contrasting with the concertino (the smaller group of soloists).