Many measurement instruments have technical specifications and datasheets that say, for example, “Accuracy: 4 %”. This is an inappropriate use of the term “accuracy” because an “accuracy” is not a quantity and cannot be assigned a value. This document describes how to use the term “accuracy” correctly, as well as giving examples of acceptable expressions that could be used in place of the incorrect expression used in the example here. Furthermore, some other commonly misused terms are discussed, and examples of correct use are given.[more]