centro-, centr-, centri-, kentro-

(Greek > Latin: center; middle point, mid point; focus, focal point, focalize; zero in on)

This element originally meant "sharp point, goad" or "spur".

geocentric longitude (s) (noun), geocentric longitudes (pl)
The angular distance in degrees that a celestial object lies east or west of Greenwich Meridian, or the meridian passing through Greenwich (Greater London borough on the Thames in England: The geocentric longitude was internationally adopted as the Earth's zero of longitude in 1884.
geocentric parallax, diurnal parallax (s) (noun); geocentric parallaxes;, diurnal parallaxes (pl)
The change in an astronomical object's apparent position: A geocentric parallax is caused by the change in the observer's earthly position because of the motion of the Earth during the day.
geocentric theory (s) (noun) (no pl)
In history, the ancient belief that the sun and other bodies of the solar system revolve around the Earth: The geocentric theory was stated in detail by Ptolemy about 140 A.D. and later replaced by the heliocentric theory of Copernicus.
geocentric zenith (s) (noun), geocentric zeniths (pl)
The point at which a line from the center of the Earth through a point on its surface meets the celestial sphere: The geocentric zenith Mr. Tall showed his class was viewed on a model of the universe.
geocentrism (s) (noun) (no pl)
The belief that the Earth is the center of the universe: The opinion that the sun revolved around the Earth and that the Earth was stationary was all the rage in Galileo's day.
geographical center (s) (noun) (no pl)
The point on which a given area on the Earth would balance: Debbie read about a geographical center in her textbook to be a spot on the Earth which would balance if if were a plate of uniform thickness.
geometric concentration ratio (s) (noun), geometric concentration ratios (pl)
The ratio (elation in degree or number between two similar things) of a solar collector aperture area (amount of light admitted) to the absorber area or the surface on a solar collector that absorbs solar radiation: Jeff learned thatt a geometric concentration ratio was the ration or relation between a section of the photosensitive part of a solar cell and the complete area of that cell.
Holding women as the center of thoughts or activities.
heliocentric (adjective), more heliocentric, most heliocentric
A reference to being focused on the sun.
heliocentric coordinates (pl) (noun), no singular
A rule for designating each point in space by a set of numbers that are relative to how far something is to the sun as a center.
heliocentric theory (s) (noun), heliocentric theories (pl)
The principle that the earth and other planets revolve around the sun: following the work of Copernicus in the 16th century.

This replaced the earlier geocentric (earth-centered) system described by Ptolemy (c. A.D. 100-170).

Ptolemy was a Greek philosopher who presented a widely accepted model of the solar system known as the "Ptolemaic system". He also made important contributions to geography and cartography.

The "Ptolemaic system" was a theory developed by Ptolemy, about A.D. 150, maintaining a motionless earth is the center of the universe with sun, moon, and planets revolving, around it; while the fixed stars are attached to an outer sphere concentric with the earth. This model was generally accepted in the West until the establishment of the "Copernican theory" about 1500 years later.

Nicolaus Copernicus (1473-1543), is the Latinized version of the name Mikolaj Kopernik, the Polish astronomer who established the heliocentric model of the solar system; that is, the principle that the sun (not the earth) is the central point to which the motions of the planets are to be referred.

Copernicus was recognized as the first person in history to create a complete general arrangement of the solar system (Copernican system); combining mathematics, physics, and cosmology.

Used to describe circles and spheres that have the same center.
iconocentrism (s) (noun), iconoceentrisms (pl)
The belief or attitude that images (or icons) are or should be the central element in the universe: "Believers of iconocentrism believe images play the most important role in their religions, other things (the deity, people, objects, or text, perhaps) being subservient to them."
ion concentration, ion density, ionization density
1. In atmospheric electricity, the number of ions per unit volume of a given sample of air; more particularly, the number of ions of given type (positive small ion, negative small ion, positive large ion, etc.) per unit volume of air.
2. The number of ions per unit volume.
3. The density of ions in a gas.