What does demagnetise mean?
Demagnetise means to strip an object of its magnetic properties, or to wipe away information stored magnetically on tape or similar media. An item becomes magnetised when its atomic domains align in a common direction — a state that can be undone by heating it past a certain point, striking it, or exposing it to a steadily weakening alternating magnetic field. Engineers demagnetise tools so stray fields do not disturb delicate instruments; watchmakers demagnetise watches whose accuracy has been ruined by proximity to magnets; and audio archivists must guard against recordings being accidentally erased by nearby equipment. The verb is closely associated with the synonym "degauss", named after Carl Friedrich Gauss, which dominates informal and technical speech, particularly in naval and computing circles. British English spells the word demagnetise while American English uses demagnetize. It is a precise, technical term, neutral in tone, and indispensable wherever unwanted magnetism is a genuine problem.
verbTo remove the magnetic properties from an object, or to erase a magnetic recording from tape or other storage medium.
- To remove the magnetic properties from an object, typically by exposure to heat, an alternating current, or a reversing field.
- To erase data recorded magnetically, such as on audio or video tape.
"The technician had to demagnetise the screwdriver before working on the hard drive."
"Watchmakers routinely demagnetise their tools, since even slight magnetism can throw off the movement of a precision timepiece."
"The archive tapes were accidentally demagnetised when they were stored too close to a powerful speaker."
Your CRT television once needed 'degaussing' — the same process as demagnetising — and old TVs literally hummed themselves clean with a coil of wire every time you switched them on.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of demagnetise
Demagnetise combines the prefix "de-" (from Latin, indicating removal or reversal) with "magnetise", itself derived from "magnet". The word "magnet" traces back through Latin magnes to Greek Magnēs lithos, meaning "stone of Magnesia", a region in Thessaly where naturally magnetised lodestone was found. The verb emerged in the nineteenth century as scientists developed a systematic vocabulary around electricity and magnetism. Its cognates include magnet, magnetic, and magnetism, all sharing the same Greek root.
Related word forms
How demagnetise is actually used
"Demagnetise" is chiefly British spelling; American English prefers "demagnetize". In technical contexts such as shipping, engineering, and audio recording, "degauss" is often used interchangeably, especially for erasing magnetic media. The word carries a neutral, technical register.
Easily confused with demagnetise
Demineralise means to remove minerals from something, whereas demagnetise means to remove magnetism.
Magnetise means to give an object magnetic properties, the opposite of demagnetise which removes them.