Английский Этимологический словарь - meridian

- c.1350, from O.Fr. meridien, from L. meridianus "of noon, southern," from meridies "noon, south," from meridie "at noon," altered by dissimilation from pre-L. *mediei die, loc. of medius "mid-" + dies "day." Originally in Eng. meaning "noon," cartographic sense first recorded 1391.