What is "permeance"

Permeance \Per"me*ance\, n. [See Permeant.] Permeation; specif. (Magnetism), the reciprocal of reluctance.

n. 1 A measure of the degree to which a material allows a fluid to permeate it. 2 (context physics English) The reciprocal of reluctance in a magnetic circuit; the analogue of conductance in an electrical circuit.

Permeance, in general, is the degree to which a material admits a flow of matter or energy. Permeance is usually represented by a curly capital P: P.