Premature ovarian failure (POF) is a condition characterized by the loss of normal ovarian function before the age of 40. The term Primary ovarian insufficiency (POI) is now preferred because it more accurately reflects the spectrum of ovarian dysfunction, including intermittent ovarian activity, rather than a complete and permanent failure.

- Primary ovarian insufficiency refers to the diminished or absent ovarian function in women under 40 years of age, leading to irregular or absent menstrual periods and infertility.
- It is important to differentiate POI from other conditions that affect ovarian or reproductive function:
- Polycystic ovary syndrome (PCOS) is a metabolic and hormonal disorder characterized by ovulatory dysfunction but typically with preserved ovarian reserve.
- Turner syndrome is a chromosomal disorder (45,X) associated with gonadal dysgenesis but is distinct from POI in its genetic and clinical presentation.
- Hypogonadotropic hypogonadism involves insufficient secretion of gonadotropins from the pituitary gland, leading to secondary ovarian failure, but this is a different pathophysiological mechanism.

In summary, the disorder synonymous with premature ovarian failure is Primary ovarian insufficiency, which encompasses the clinical and biological features of early ovarian dysfunction.