Conductivity \Con`duc*tiv"i*ty\ (k[o^]n`d[u^]k*t[i^]v"[i^]*t[y^]), 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.

Source: Webster's Revised Unabridged Dictionary (1913)