temperamentum

Temperamentum is a Latin noun meaning temperament, disposition, or mixture, derived from temperare, to regulate or mix. In historical contexts the term is used to denote two related ideas: a person’s temperament or disposition and a set of tuning rules in music.

In medicine and psychology, temperamentum referred to the idea that individuals have innate dispositions shaped by the balance of bodily fluids, or humors. Classical and medieval writers described four temperaments: sanguine, phlegmatic, choleric, and melancholic. Each temperament was associated with particular traits and with the predominance of a humor. Treatments, diets, and activities were chosen to restore balance according to the patient’s temperament.

In music, temperamentum denotes tuning systems used to adjust the size of intervals in order to make keyboard music playable in several keys. Medieval and early modern scholars discussed temperaments as compromises between pure intervals and the practical needs of modulation. Well-known temperaments include those that attempt to balance interval sizes across keys, though the Latin term is mostly encountered in historical texts rather than in modern usage.

Other uses of temperamentum occur in alchemy, metallurgy, and philosophy to express the idea of tempering or balancing substances or qualities. In contemporary English scholarship the Latin term is often replaced by temperament or temperatio, while temperamental as an English descendant remains common in reference to mood or disposition.