The term 'encephalon' is a synonym for the word 'BRAIN'. It is derived from the Greek words enkephalos, meaning 'in the head', and nous, meaning 'MIND'. The BRAIN is the most complex organ in the human body, and is responsible for controlling and coordinating all of the body's activities. It is composed of billions of neurons that communicate with each other to process information and generate thoughts, feelings, and behavior. The BRAIN is also responsible for regulating bodily functions such as breathing, heart rate, and digestion.