Menopause refers to:

Menopause is defined as the cessation of menstruation, marking the end of a woman's reproductive years. It typically occurs between the ages of 45 and 55 and signifies that the ovaries have stopped releasing eggs and producing significant amounts of hormones like estrogen and progesterone. This biological transition results in the discontinuation of menstrual cycles and can come with various symptoms such as hot flashes, mood changes, and sleep disturbances.

The other options pertain to different aspects of sexual health and aging. The loss of male sexual potency is related not to menopause but to andropause or other age-related changes in men. Irregular timing of menstrual periods may occur as women approach menopause, but it does not define menopause itself; instead, it is often a symptom leading up to it. The loss of sexual interest in late adulthood can happen for various reasons but is not exclusive to or synonymous with menopause. Thus, the correct answer encapsulates the primary definition of menopause clearly and accurately.