meridian
In full celestial meridian: a great circle passing through the poles of the celestial sphere and the zenith for a particular point on the Earth's surface.
Other meanings
In full terrestrial meridian: a great circle on the Earth's surface, passing through the geographic poles (the terrestrial North Pole and South Pole); also, half of such a circle extending from pole to pole, all points of which have the same longitude.
The place on the celestial meridian where it is crossed by the sun or a star at its highest point.
Synonyms
- line of longitude
Word history
From Middle English "meridian".
Where this comes from
This definition is adapted from “meridian” on Wiktionary, by its contributors; related-word lists use Open English WordNet (CC BY 4.0, based on Princeton WordNet), published under CC BY-SA 4.0. This page is published under the same licence.