noun. A measure of the ability of a material to interact with an electric field and become polarized by the field, so that the field within the material is weaker than the field in the absence of the material. The permittivity of a material is the product of the dielectric constant of the material and the permittivity of a perfect vacuum, which is defined to be about 8.854 × 10⁻¹² farad per meter.

noun. In elec., degree of permittance; the ratio of permittance of a dielectric to that of air.

noun. In electricity, degree of permittance; the ratio of permittance of a dielectric to that of air.

noun. A property of a dielectric medium that determines the forces that electric charges placed in the medium exert on each other.

"This ability is represented by constants or fixed quantities that are called the permittivity (for electricity) and permeability (for magnetism)."

permittivity of free space  

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