Added 9 October 2026

meridian

/məˈɹɪ.dɪ.ən/ noun

In Latin: meridianus Wiktionary

noun Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about meridian at Wordnik → Where our words come from →

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. .mw-parser-output .defdate{font-size:smaller} 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.
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. .mw-parser-output .defdate{font-size:smaller}
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.

Any of the pathways on the body along which chi or qi (life force) is thought to flow and, therefore, the acupoints are distributed; especially, one of twelve such pathways associated with organs of the body.

The noun is derived from Late Middle English meridian, meridien (“midday, noon; position of the sun at noon; the south; longitude of a place; (astronomy) celestial meridian”) [and other forms], from Anglo-Norman meridien (“midday”), Middle French meridien (“midday; the south; terrestrial meridian; (astronomy) celestial meridian”) (modern French méridien), and Old French meridiane, meridiiene, and from their etymon Latin merīdiānum (“midday; position of the sun at noon; the south”), a noun use of the neuter form of merīdiānus (“relating to midday; southern”); see further at etymology 1. Sense 1.1 (“celestial meridian”) is ultimately modelled after Latin merīdiāna līnea (“meridian line”).