What does coercivity mean?
Coercivity is a technical property in physics that quantifies how strongly a magnetic material resists being demagnetized. Specifically, it is the intensity of the reverse magnetic field required to bring a ferromagnetic material's magnetization down to zero. Materials with high coercivity — such as neodymium and samarium-cobalt alloys — hold their magnetism firmly once magnetized, making them ideal for permanent magnets in motors, loudspeakers, and wind turbines. Materials with low coercivity, by contrast, magnetize and demagnetize easily, which suits them to applications like transformer cores where the magnetic state must reverse constantly. Engineers often describe this property as 'coercive force,' and it is measured in units such as amperes per metre or oersteds. The term derives from the same Latin root as 'coerce' — literally 'to restrain or confine' — a fitting origin for a word describing a material's refusal to give up its magnetic state. Though confined almost entirely to scientific and engineering registers, coercivity is essential vocabulary in magnetics and data-storage technology.
nounThe intensity of a magnetic field required to reduce the magnetization of a ferromagnetic material to zero; a measure of a material's resistance to demagnetization.
- The magnetic-field intensity needed to demagnetize a ferromagnetic material completely, used as a key measure of permanent-magnet quality.
"Neodymium magnets are prized for their high coercivity, which allows them to retain magnetism even in hostile environments."
"Hard drive platters are coated with materials chosen for high coercivity so that stored data resists accidental erasure."
"Engineers selected a ferrite with low coercivity for the transformer core, allowing it to be easily remagnetized each cycle."
Rarely pluralized; used only when comparing values across different materials.
"The table lists the coercivities of several commercial magnet alloys."
A magnet's stubbornness has a number: coercivity measures exactly how much opposing force it takes to make a magnet forget its own magnetism.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of coercivity
Coercivity comes from the Latin verb coercēre, meaning 'to restrain, confine, or surround', formed from com- ('together') + arcēre ('to keep off or enclose'). English borrowed 'coerce' via French/Latin in the 15th–17th centuries, and the noun coercivity was later formed in the scientific era as the magnetic analogue of 'coercive force'. It shares its root with coercion, coercive, and distantly with exercise (from Latin exercēre).
Related word forms
How coercivity is actually used
Strictly a technical term from physics and materials science, rarely encountered outside engineering contexts such as magnetics, data storage, and electronics. It is an uncountable noun and carries no figurative or everyday usage.
Easily confused with coercivity
Coercion is the act of forcing someone to do something through threats or pressure, while coercivity is a physical property measuring a material's resistance to being demagnetized.