In all branches of science and technology people need to choose their vocabulary with care. Each term must have the same meaning for all of its users, and also express a well-defined concept which is not in conflict with everyday language. Every measurement is influenced by errors which are not completely known and this leads to measurement uncertainty. It is important to take account of this uncertainty when expressing the significance of a measurement. We must therefore precisely describe the impreciseness of the measurement itself.

The following article provides a set of important terms to be well understood and properly used by everyone involved in measurements.