1. Of, belonging to, or peculiar to, autumn; as, an autumnal tint; produced or gathered in autumn; as, autumnal fruits; flowering in autumn; as, an autumnal plant. Thick as autumnal leaves that strow the brooks in Vallombrosa. (Milton)
2. Past the middle of life; in the third stage. An autumnal matron. (Hawthorne) autumnal equinox, the time when the sun crosses the equator, as it proceeds southward, or when it passes the ~ point. ~ point, the point of the equator intersected by the ecliptic, as the sun proceeds southward; the first point of libra. ~ signs, the signs libra, scorpio, and sagittarius, through which the sun passes between the ~ equinox and winter solstice.