Major affective disorder, commonly known as mood disorder, is a mental health disorder that affects a person's emotions, mood, and energy levels. This condition is characterized by extreme changes in mood, including periods of depression, sadness, or mania. There are various synonyms used for major affective disorder, including bipolar disorder, manic-depressive illness, clinical depression, and major depressional disorder. These synonyms are often used interchangeably but have slight differences in symptoms and treatments. Regardless of the terminology used, seeking proper diagnosis and treatment is critical for managing major affective disorders and improving overall mental health and wellbeing.