n. A period of life characterized by physiological and psychic change that marks the end of the reproductive capacity of women and terminates with the completion of menopause.n. A corresponding period sometimes occurring in men that may be marked by a reduction in sexual activity, although fertility is retained.n. A critical period or year in a person's life when major changes in health or fortune are thought to take place.n. A critical stage, period, or year: "before the end of the millennium, whether [he] lives to see that ecclesiastical climacteric or not” ( Conor Cruise O'Brien). adj. Of or relating to a climacteric.adj. Critical; crucial.