How do perimenopause, menopause, and post menopause differ from one another?

Menopause definition: The medical definition of menopause is one year with no bleeding or spotting--then, you can consider yourself menopausal (or the term post-menopausal can also be used). Peri-menopause is the interval of several years (3-5 years) during which periods become irregular prior to the final menstrual period (which is not easy to predict).