Con·duc·tiv·i·ty n. The quality or power of conducting, or of receiving and transmitting, as heat, electricity, etc.; as, the conductivity of a nerve.
Thermal conductivity Physics, the quantity of heat that passes in unit time through unit area of a plate whose thickness is unity, when its opposite faces differ in temperature by one degree. --J. D. Everett.
Thermometic conductivity Physics, the thermal conductivity when the unit of heat employed is the heat required to raise a unit volume of the substance one degree.