me ‧ rid ‧ i ‧ an /məˈrɪdiən/ BrE AmE noun
[ Date: 1300-1400 ; Language: Old French ; Origin: Latin meridianus 'of the middle of the day' , from medius 'middle' + dies 'day' ]
1 . [countable] one of the imaginary lines from the North Pole to the South Pole, drawn on a map of the Earth
2 . the meridian technical the highest point reached by the sun or another star, when seen from a point on the Earth’s surface