English horn, musical instrument, the alto of the oboe family, pitched a fifth lower than the oboe and treated as a transposing instrument. It has a pear-shaped bell, giving it a soft, melancholy tone. The first important parts for it were written by Rossini in William Tell (1829) and by Meyerbeer in Robert le diable (1831). Other composers, notably Wagner, have used it in opera and orchestral music. The 18th-century form of the instrument was curved, whence, possibly, its misleading designation as a horn. In Britain and Europe it is often termed cor anglais.