Dieelectric constant
“The dielectric constant is defined as a measure of a material's ability to store electrical energy in an electric field, which can be represented through the effective dielectric constant of a composite material as discussed in spectral representation theory.” (Huang and Yu 2006)
Sources
Huang, J. P., and K. W. Yu. 2006. “Enhanced Nonlinear Optical Responses of Materials: Composite Effects.” Physics Reports 431 (3): 87–172. doi:10.1016/j.physrep.2006.05.004.