The term 'Cousin of a Cor Anglais' is a reference to the OBOE, which is a four-letter word. The OBOE is a double-reed woodwind instrument that is part of the larger family of instruments known as the OBOE family. It is similar to the cor anglais, which is a larger version of the OBOE, and is often referred to as the 'English horn'. The OBOE is used in many types of music, including classical, jazz, and folk music. It is also used in film scores and other soundtracks.