The term 'UPPER PART OF THE MOUTH' can be summarized as the ROOF of the mouth, which is a four letter word. The ROOF of the mouth, also known as the hard palate, is the bony structure that separates the nasal cavity from the oral cavity. It is composed of two parts: the anterior portion, which is made up of bone, and the posterior portion, which is made up of soft tissue. The ROOF of the mouth plays an important role in speech production and swallowing.