Thermal conductivity and resistivity
The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k {\displaystyle k} , λ {\displaystyle \lambda } , or κ {\displaystyle \kappa } and, in SI units, is measured in W·m−1·K−1.
Source: Wikipedia — Thermal conductivity and resistivity (CC BY-SA 4.0)