affectus

Affectus is a Latin noun and participial form meaning state, condition, feeling, or disposition. In classical Latin it denotes an inner state of the mind or body, often translated as “affection,” “emotion,” or “mood.” The term occurs in philosophical and medical authors to describe passions or affections of the soul and body, and it was commonly used in treating illnesses as distortions or passions of organs or faculties.

In medieval and early modern scholastic thought, affectus was central to discussions of the passions (passiones) and their ethical and volitional implications, sometimes contrasted with voluntas (will) and intellect. The vocabulary of affect developed into broader Latin and vernacular terms for emotion, influencing the modern concept of affect in psychology and linguistics. The English word affect is ultimately derived from affectus and is used to denote either the experienced emotion (feeling) or the observable expression of emotion (mood, demeanor).

In contemporary psychology, affect refers to the broad spectrum of emotion and mood and is distinguished from more stable traits such as temperament. Psychiatrists discuss affect as an aspect of a patient’s emotional state, including qualitative variations (for example, constricted or expansive affect) and its congruence with thought content.