What does demagnetised mean?
Demagnetised describes an object that has been stripped of its magnetic properties, either naturally over time or deliberately through exposure to heat, alternating current, or opposing magnetic fields. It functions both as the past tense and past participle of the verb demagnetise and as an adjective describing the resulting state. The term appears most often in scientific and industrial settings: engineers demagnetise tools before repairing sensitive electronics, hospitals ensure instruments are fully demagnetised near MRI machines, and audio technicians once degaussed (demagnetised) tape heads to preserve sound quality. The word derives from magnet, ultimately from the Greek Magnēs lithos, the 'stone of Magnesia', a region known for its naturally magnetic lodestone. Its connotations are neutral and precise rather than emotional, making it a staple of technical writing. The American spelling is demagnetized with a z, while British English favours the -ise ending seen here.
Past tense and past participle of demagnetise: removed the magnetic properties from something.
"She demagnetised the metal strip before disposal."
Describing an object that has had its magnetism removed.
"Keep all demagnetised equipment away from the compass calibration bench."
Wipe a credit card's stripe across a strong magnet and you've demagnetised it — the same principle that once erased wartime shipping records.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of demagnetised
Demagnetised combines the prefix de- (Latin, meaning removal or reversal) with magnetise, which itself derives from magnet, borrowed via Latin magneta from Greek Magnēs lithos ('Magnesian stone'), referring to lodestone from the region of Magnesia in Thessaly. The compound form arose in the 19th century alongside growing interest in electromagnetism, as scientists and engineers needed a term for deliberately destroying magnetic properties. Cognates include magnetism, magnetic, and magnetisation, all sharing the same Greek root.
Related word forms
How demagnetised is actually used
Primarily technical and formal register, common in physics, engineering, and electronics contexts. The British spelling uses -ise; American English uses -ize.
Easily confused with demagnetised
De-mobilised means released from military service, whereas demagnetised means having lost magnetic properties.