APA Dictionary of Psychology

in psychoanalytic theory, a fundamental element of the sexual instinct that has a specific source in one part of the body (e.g., the oral instinct) and a particular aim (e.g., instinct to master). The component instincts are posited to function independently during the early stages of psychosexual development and later to fuse during the genital stage, which begins at puberty. Also called partial instinct; part instinct.