n. (from Latin meridie, "at noon", from medius "mid-" + dies "day")

Latin term for midday; noon; twelve o'clock noon (12:00PM); the midpoint of a twenty-four hour day, which is twelve hours and zero minutes (12:00).

Though mostly obsolete in the United States, it remains, in certain other countries, one of the scientific diurnal designations used in nautical travel, aerial travel, and inland celestial navigation.