A physical quantity measuring a change of internal energy with respect to the change of its entropy :

T = \left(  \frac{\partial U}{\partial S} \right)_{V,N}

with other state variables (volume and number of particles ) being constant.

Symbol	Dimension	SI units	Oil metric units	Oil field units
T	Θ	K	°C = K - 273	°F = 9/5 T [°C] + 32

See also