demagnetize
verb
de·mag·ne·tize (ˌ)dē-ˈmag-nə-ˌtīz 
demagnetized; demagnetizing; demagnetizes
transitive verb
: to deprive of magnetic properties
demagnetization
(ˌ)dē-ˌmag-nə-tə-ˈzā-shən
noun demagnetizer
(ˌ)dē-ˈmag-nə-ˌtī-zər
noun 
Example Sentences
Recent Examples on the Web Conclusion: the live cockroaches demagnetize (i.e., the magnetic field decays) much faster than dead ones. 
Jennifer Ouellette, Ars Technica, 12 Sep. 2019 The basic theory was that the flowing hot water demagnetized the minerals. Chris Lee, Ars Technica, 11 Oct. 2017 The earth’s solid iron core is hot enough to demagnetize iron and its alloys. Katie Nodjimbadem, Smithsonian, 29 June 2017 The earth’s solid iron core is hot enough to demagnetize iron and its alloys. Katie Nodjimbadem, Smithsonian, 25 May 2017
Jennifer Ouellette, Ars Technica, 12 Sep. 2019 The basic theory was that the flowing hot water demagnetized the minerals. Chris Lee, Ars Technica, 11 Oct. 2017 The earth’s solid iron core is hot enough to demagnetize iron and its alloys. Katie Nodjimbadem, Smithsonian, 29 June 2017 The earth’s solid iron core is hot enough to demagnetize iron and its alloys. Katie Nodjimbadem, Smithsonian, 25 May 2017 Word History
First Known Use
1839, in the meaning defined above