The term 'Parts of Psyches' refers to the three components of Sigmund Freud's psychoanalytic theory. These components are the Id, Ego, and Superego. The Id is the unconscious part of the psyche that seeks immediate gratification and is driven by instinct. The Ego is the conscious part of the psyche that mediates between the Id and the Superego. The Superego is the moral part of the psyche that is driven by social norms and values. In crossword puzzles, the solutions for these terms are IDS (3 letters) and EGOS (4 letters).