What property of an insulating material heavily influences the extent of energy absorption loss in the dielectric?

Answer

Dissipation factor ($ ext{Df}$ or $ an ext{ } ext{ } ext{ extgreek{d}}$).

Dielectric loss, caused by molecular realignment within the insulator absorbing signal energy, depends heavily on the material's dissipation factor ($ ext{Df}$).

What property of an insulating material heavily influences the extent of energy absorption loss in the dielectric?
resistanceSignalLosscircuitAttenuation