A degree of freedom is an independent physical parameter in the formal description of the state of a physical system.
In three-dimensional space, three degrees of freedom are associated with the movement of a particle.
A diatomic gas molecule thus has six degrees of freedom. This set may be split in terms of translations, rotations, and vibrations of the molecule. The centre of mass motion of the whole molecule accounts for three (3) degrees of freedom. Also, the molecule has two rotational degrees of motion and one vibrational degree of freedom.
