1 Density or Mass density:

Density or mass density of a fluid is defined as the ratio of the mass of a fluid to its volume. Thus mass per unit volume of a is called density.

2. Specific weight or weight density:

Specific weight or weight density of a fluid is the ratio between the weight of a fluid to its volume. The weight per unit volume of a fluid is called weight density.

3. Specific Volume:

Specific volume of a fluid is defined as the volume of a fluid occupied by a unit mass orvolume per unit mass of a fluid

4.Specific Gravity:

Specific gravity is defined as the ratio of the weight density of a fluid to the weight density of a standard fluid.