meridian
The word 'meridiano' in Spanish translates to 'meridian' in English. In geography, a meridian (or line of longitude) is an imaginary line on the earth's surface from the North Pole to the South Pole that indicates the east-west position of a point on the earth's surface. Meridians are part of the coordinate system used to map the earth's surface.
The sun reaches its highest point in the local meridian.
This sentence refers to the peak of solar culmination when the sun appears the highest in the sky, which occurs when it crosses the local meridian.
The meridian line determines the local time.
This sentence explains how local time is set according to the meridian line, which is an imaginary line used for that purpose in geography.
The meridian passes through Greenwich in London.
This sentence is referencing the Prime Meridian which passes through Greenwich, London, and against which all geographical longitudes are measured.