B Flat is a musical NOTE and is also known as Si in the French solfège system. It is the seventh NOTE of the C major scale and is a half step below C. In the German system, it is referred to as B. The term B Flat is also used to refer to a musical key, which is a set of notes that are related to each other. The term B Flat can also be used to refer to a type of musical instrument, such as a saxophone or clarinet. The term B Flat is also used in the title of a poem by Bret Harte, which is a five-letter word.