Final answer:
Perfect order (APICS DEF) is a concept in Mathematics that involves the constant pi (π) and the difference in pressure (AP). It relates to equations or expressions that use pi and pressure in specific ways.
Step-by-step explanation:
Perfect order (APICS DEF) refers to a concept in Mathematics that represents the mathematical constant pi (π), which is the ratio of a circle's circumference to its diameter. The letter AP in the term represents the difference in pressure. In this context, DEF can be any expression or equation that relates to the specific problem or situation being discussed. For example, DEF could represent a formula or equation that involves pi and pressure.