magnet-, magneto- +

(Greek: Magnesian [stone]; Magnesia having been a mineral-rich region of Thessaly)

geomagnetically
Relating to terrestrial magnetism.
geomagnetism
1. The various magnetic things that happen when they are generated by the earth and its atmosphere; and by extension, the magnetic phenomena in interplanetary space.
2. A branch of geology concerned with the magnetic properties of the earth.
gyromagnetic
1. Relating to or caused by the magnetism produced by the spinning motion of a charged particle.
2. Resulting from the magnetic properties of a spinning, electrically charged particle.
hydromagnetics, hydromagnetic
The study of the interaction of magnetic fields and electrically conducting liquids or gases; such as, molten metal or plasma.
magnet
1. An object that is surrounded by a magnetic field and that has the property, either natural or induced, of attracting iron or steel.
2. An object made of iron oxide or steel which attracts iron and has polarity.
3. An electromagnet.
4. A person, a place, an object, or a situation that exerts strong attraction.

A peculiar stone from the neighborhood of the town of Magnesia, in Thessaly, Greece, which had the power of attracting small pieces of iron

The ancients, including Homer and Plato, knew about the "magnet" or the stone which they called magnes, from the name of the town, or more frequently, lithos Magnetis, "stone of Magnesia" from which we inherited the word "magnet".

It had two specific applications: to ore with magnetic properties, and to stone with a metallic sheen. It was the first of these that has come down to English via Latin magneta.

English magnesia came from the same source, but it is not clear how it came to be applied (in the 18th century) to "magnesium oxide" because it originally referred to a "constituent of the philosopher's stone; in the vague terminology of the alchemists.

In the 17th century, it was used for "manganese" which came via French from Italian manganese, an alteration of medieval Latin magnesia.

When the term magnesium was introduced at the suggestion of the chemist Sir Humphry Davy, it also denoted "manganese" in the beginning.

There is no evidence that the Greeks put the peculiar characteristics of the stone to any use; in fact, the first European record of any applications of the properties of the magnet is not found before the end of the twelfth century A.D.

The first European mention of a magnetized needle and its use among sailors occurs in Alexander Neckam's De naturis rerum (On the Natures of Things), probably written in Paris in 1190.

Through the use of the compass, this "stone of Magnesia" or magnes came to be known as a lodestone because, like the lodestar, it pointed the way (from the Middle English word lode, "way").

William Gilbert, in 1600, was the first to produce a scientific study of magnetism.

—Based on information from
Thereby Hangs a Tale by Charles Earle Funk;
Harper & Row, Publishers; New York; 1950; page 182
and
Dictionary of Word Origins by John Ayto;
Arcade Publishing; New York; 1990; page 333.
magnetic
Associated with or produced by a magnet or the property of magnetism.
magnetic field, magnetic force
A vector field (a quantity that has both direction and magnitude, e.g. force or velocity, usually represented by an arrow) occupying physical space in which a magnetic force can be detected, typically in the presence of a permanent magnet, current-carrying conductor, or electromagnetic wave.
magnetic pole
1. Either of two points on the earth's surface at which the manettic dip is exactly 90 degrees>
2. The point where the meridians join; for example, where the magnetic field is vertical.
magnetic resonance imaging (MRI)
1. A type of diagnostic radiography using electromagnetic energy.

Certain atomic nuclei with an odd number of neutrons, protons, or both are subjected to a radio-frequency pulse, causing them to absorb and release energy.

2. A non-invasive method of imaging the body and its organs; as well as, studying tissue metabolism.

More details about MRI

The body is placed in a magnetic field which causes certain atomic nuclei to align in the direction of the field. Pulses of radio-frequency radiation are then applied; interpretation of the frequencies absorbed and re-emitted allows an image in any body plane to be built up.

Different tissues; for example, fat and water, can be separately identified and, if the resonance signal for the fat is suppressed, then only the signal from any abnormalities in the fat can be identified.

Many diseases result in a rise in the water content of tissues; so, MRI, or magnetic resonance imaging, is a valuable test for identifying certain diseases.

—Information for this section comes from
Black's Medical Dictionary; 41st Edition;
Edited by Dr. Harvey Marcovitch; The Scarecrow Press, Inc.;
Lanham, Maryland; 2006; page 451.
magnetism
The phenomenon by which materials will have either an attracting or repelling force with respect to other materials.

This occurs when electrically charged particles are in motion, either from their movement in an electric current or from their presence in a permanent magnet (a substance or object that retains its own magnetic properties).

Certain metals are observed to have a strong property of magnetism.

magneto
An electric generator containing one or more permanent magnets, which provide the magnetic flux (the lines of magnetic force arising from and found in the vicinity of a magnetized body).
magnetofluid
Any liquid that becomes less fluid under the influence of a magnetic field.
magnetogram
A graphic representation of magnetic field strengths and polarity.
magnetohydrodynamics, magnetohydrodynamic; MHD
1. The study of the interaction of magnetic fields and electrically conducting liquids or gases; such as, molten metal or plasma.
2. A theoretical procedure that would drive warships and submarines in seawater by having the water enter a cylindrical duct running through the hull and the interaction between a vertical magnetic field and an electric current passing horizontally through the water in the duct which pushes the water out of the stern, generating thrust.
magnetopause
The outer layer of the earth's magnetosphere, bordering the solar wind.