Coercivity, normal: HcB
The field strength required to reduce the magnetic induction of a magnetic material to zero
Coercive field strength Hc
Only when the externally applied field strength has reached an oppositely directed value - the coercive field strength Hc - does the magnetization B = 0 and the product is demagnetized. The area of the loop passed through with alternating magnetization is a measure of the loss. Materials with low values of Hc and therefore small hysteresis loops are called soft magnetic materials. If Hc is very large, they are called hard magnetic material.
For more information see the explanation under hysteresis curve.