reluctivity
/ˌriːlʌkˈtɪvɪti/Magnetism and Electricity
noun
One of the physical parameters of a magnetic material, equal to the reluctance per unit volume and equivalent to the reciprocal of magnetic permeability.
Origin
Late 19th century; earliest use found in Oliver Heaviside (1850–1925), physicist and electrical engineer. From reluct- + -ivity.