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.

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.

A line passing through the poles of any sphere; a notional line on the surface of a curved or round body (in particular, an eyeball).

The place on the celestial meridian where it is crossed by the sun or a star at its highest point.

(figurative) The highest or most developed point, or most splendid stage, of something; culmination, peak, zenith.

(figurative) Chiefly followed by of: the middle period of someone's life, when they are at their full abilities or strength; one's prime.

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.

A ring or half-ring with markings in which an artificial globe is installed and may spin.

(US, old-fashioned) The size of type between double great primer and canon, standardized as 44-point.

(no longer used) Midday, noon.

(no longer used) The south.

(no longer used) A midday rest; a siesta.

(no longer used) A particular area or situation considered as having a specific characteristic or identity; also, the characteristics, habits, or tastes of a specific group, locale, etc.

(Scotland, no longer used) An alcoholic drink taken at midday.

Relating to a meridian (in various senses); meridional.

Relating to midday or noon.

(no longer used) Relating to the culmination or highest point.

(no longer used) Relating to the south; meridional, southern.

(rare) To cause an object to reach the meridian or highest point of (something).

(rare) Of a celestial body: to reach its meridian.