The term 'Mental Structure' can be defined as the psychological makeup of an individual, which is often referred to as the 'PSYCHE'. The term 'PSYCHE' is derived from the Greek word for 'SOUL' and is used to describe the mental and emotional aspects of a person. It is composed of conscious and unconscious elements, such as beliefs, values, memories, and experiences. Mental structure is important in understanding how individuals think, feel, and behave.