The word Affect is in psychology and psychiatry used to described observable behaviour that represents the expression of a subjectively experienced feeling state (emotion). Common examples of affect are

• sadness,
• fear,
• joy,
• anger.

The normal range of expressed affect varies considerably between different cultures and even within the same culture.

Types of affect include:

• euthymic,
• irritable,
• constricted,
• blunted,
• flat,
• inappropriate,
• labile.

Euthymic mood would be considered as the "normal" stable mood without complaints.

Affective Disorders are mental health disorders with observable alteration of affect (mood). This would include Major Depression, Dysthymia / Cyclothymia, Bipolar disorder and Adjustment disorders and a broader category of depressive symptoms, which do not fit in the classical categories of mood disorders (Depressive disorders not otherwise specified).