Temperament:An individual's innate and characteristic patterns of behavior, emotion, and thought, which are present from a young age and remain relatively stable throughout life.
Humoral Theory: An ancient Greek medical theory that proposed four bodily fluids (humors) - blood, phlegm, yellow bile, and black bile - whose balance or imbalance determined a person's temperament and health.
Extraversion:A personality trait characterized by a focus on the external world, sociability, assertiveness, and a tendency to experience positive emotions.