Amount of heat required to change the temperature of one unit of mass with the constant volume by one unit of temperature:
c_V = \left( \frac{\delta Q}{\delta m \cdot \delta T} \right)_V |
It is a material property and properly tabulated for the vast majority of materials.
See also
Physics / Thermodynamics / Thermodynamic process / Heat Transfer / Heat Capacity / Specific heat capacity
[ Isobaric specific heat capacity (cmp) ]
[ Basic Petroleum Rock and Fluid Properties Handbook ]