Thickness is a physical property that can be measured in various ways. HARDNESS, GAUGE, WIDTH, BREADTH, BULK, MEASUREMENT, DIAMETER, caliper, DENSITY, LAYER, and PLY are all terms used to describe thickness. HARDNESS is the measure of how resistant a material is to deformation or indentation. GAUGE is a unit of MEASUREMENT used to measure the thickness of sheet metal or wire. WIDTH is the distance from one side to the other of an object. BREADTH is the measure of how wide something is. BULK is the measure of how much space an object takes up. MEASUREMENT is the act of measuring something. DIAMETER is the distance across the middle of a circle. Caliper is a device used to measure the thickness of an object. DENSITY is the measure of how much mass an object has per unit of volume. LAYER is a thin sheet of material. PLY is a unit of MEASUREMENT used to measure the thickness of fabric.