In music, the term adagio means played slowly. If a symphony has an adagio movement, it's a section that's played at a slow tempo.
Adagio can be an instruction on a piece of sheet music, directing the musician to play slowly, or it can be a description of a musical interlude. Sometimes a composition has the word adagio in its title, like Samuel Barber's "Adagio for Strings." The origin of adagio is the Italian phrase ad agio, in which ad means "at" or "to," and agio means "leisure."