The term 'Cousin of the English Horn' is referring 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 English horn, but has a narrower bore and a higher pitch. The OBOE is used in orchestras, concert bands, chamber music, and jazz ensembles. It is also popular in folk music and traditional music.