An aria ([ˈaːrja]; Italian: air; plural: arie [ˈaːrje], or arias in common usage, diminutive form arietta [aˈrjetta] or ariette) in music was originally any expressive melody, usually, but not always, performed by a singer. The term became used almost exclusively to describe a self-contained piece for one voice, with or without orchestral accompaniment, normally part of a larger work. The typical context for arias is opera, but vocal arias also feature in oratorios and cantatas, sharing features of the operatic arias of their periods.