meridian
n
1 imaginary circle round the earth, passing through (a given place and) the North and South Poles 子午線; 經線
the Greenwich meridian, ie longitude 0, which passes through the North and South Poles and Greenwich, England 格林威治子午線.
2 highest point reached by the sun or other star, as viewed from a given point on the earth's surface 從地面觀測太陽或其他星球到達的最高點.