**An irregular solid is defined as a three-dimensional solid object that does not have an normal shape, such as a sphere, cube or pyramid.** Irregular solids have many sides of differing lengths.

Irregular solids cannot be measured directly. The volume of such objects is determined by dropping an irregular solid in a known quantity of water. The amount of water rise equals the volume of the irregular solid. The mass of the item may not be made of homogeneous materials, such as rock. To figure out the mass density of an irregular solid, it must be broken down into different parts.

Displacing water to measure the volume of a solid is known as the Archimedes principle. The Greek mathematician Archimedes determined that the amount of water displaced by an object equals the volume of a solid. Since water has a known weight, the overall mass of the object is determined by the amount of water removed due to added volume.

Quantifying displacement of regular solids, like cubes, is done by measuring each side and multiplying the lengths. The volume of solids is referred as a "cubic" measurement in three dimensions. Solids have definite shapes, which means they rarely change over time or if the objects change position.