meridian
Cross references: 1. summit me.rid.i.an \m*-'rid-e--*n\ n [ME, fr. MF meridien, fr. meridien of noon, fr. L meridianus,] fr. meridies noon, south, irreg. fr. medius mid + dies day - more at MID, DEITY obs 1: the hour of noon : MIDDAY 2: a great circle of the celestial sphere passing through its poles and the zenith of a given place 3: a high point 4a1: a great circle on the surface of the earth passing through the poles a nd any given place 4a2: the half of such a circle included between the poles 4b: a representation of such a circle or half circle numbered for longitude on a map or globe - meridian aj
Webster's English Dictionary