A Concerto Grosso is a piece of music from the 18th century in which there are a small group of instruments and a large group of instruments. These two groups are contrasted with one another. Sometimes both play together, sometimes one plays by itself, or the two groups might imitate one another. The small group is called “concertino” and the large group is called "tutti", “ripieno” or “concerto grosso” (the same name as the musical piece). “Concerto grosso” is Italian for “big concerto”. The plural is “concerti grossi”. Notice that the second “c” in “concerto” is pronounced like an English “ch”.