working out
/ˌwəːkɪŋ ˈaʊt/noun
1The action or an act of working out or working something out.
2 Music. The unfolding of the qualities or capacities of a musical phrase or subject; the part of a piece in which this takes place.
Origin
Early 17th century; earliest use found in Robert Bolton (1572–1631), Church of England clergyman. From working + out, after to work out.