A scherzo (/ˈskɛərtsoʊ/, UK also /ˈskɜːrt-/; Italian: [ˈskertso]; plural scherzos or scherzi), in western classical music, is a short composition – sometimes a movement from a larger work such as a symphony or a sonata. The precise definition has varied over the years, but scherzo often refers to a movement that replaces the minuet as the third movement in a four-movement work, such as a symphony, sonata, or string quartet. The term can also refer to a fast-moving humorous composition that may or may not be part of a larger work.

Source: Scherzo – Wikipedia