**Measuring** – A process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity.

**Metrology** – Science of measurement and its application.

**Measurand** – Quantity intended to be measured.

**Measurement principle** – Phenomenon serving as a basis of a measurement.

**Measurement method** - Generic description of a logical organization of operations used in a measurement.

**Measurement procedure** - Detailed description of a measurement according to one or more measurement principles and to a given measurement method, based on a measurement model and including any calculation to obtain a measurement result.

**Measurement Result** - Set of quantity values being attributed to a measurand together with any other available relevant information.

**Measured quantity value** – Quantity value representing a measurement result.

**Measurement accuracy** – Closeness of agreement between a measured quantity value and a true quantity value of a measurand.

**Measurement precision** - Closeness of agreement between indications or measured quantity values obtained by replicate measurements on the same or similar objects under specified conditions.

**Measurement error** – Measured quantity value minus a reference quantity value.

**Systematic measurement error** - Component of measurement error that in replicate measurements remains constant or varies in a predictable manner.

**Random measurement error** - Component of measurement error that in replicate measurements varies in an unpredictable manner.

**Repeatability condition of measurement** –Condition of measurement, out of a set of conditions that includes the same measurement procedure, same operators, same measuring system, same operating conditions and same location, and replicate measurements on the same or similar objects over a short period of time.

**Measurement repeatability** – Measurement precision under a set of repeatability conditions of measurement.

**Intermediate precision condition of measurement** - Condition of measurement, out of a set of conditions that includes the same measurement procedure, same location, and replicate measurements on the same or similar objects over an extended period of time, but may include other conditions involving changes.

**Intermediate measurement precision** - Measurement precision under a set of intermediate precision conditions of measurement

**Reproducibility condition of measurement** - Condition of measurement, out of a set of conditions that includes different locations, operators, measuring systems, and replicate measurements on the same or similar objects.

**Measurement reproducibility** – Measurement precision under reproducibility conditions of measurement.

**Measurement uncertanity** - Non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used.

**Type A evaluation of measurement uncertainty** - Evaluation of a component of measurement uncertainty by a statistical analysis of measured quantity values obtained under defined measurement conditions.

**Type B evaluation of measurement uncertainty** - Evaluation of a component of measurement uncertainty determined by means other than a Type A evaluation of measurement uncertainty.

**Standard measuring uncertainty (standard uncertainty)** – Measurement uncertainty expressed as a standard deviation.

**Combined standard measuring uncertainty (combined standard uncertainty)** – Standard measurement uncertainty that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model.

**Relative standard measuring uncertainty** – Standard measurement uncertainty divided by the absolute value of the measured quantity value.

**Uncertainty budget** - Statement of a measurement uncertainty, of the components of that measurement uncertainty, and of their calculation and combination.

**Target measurement uncertainty** - Measurement uncertainty specified as an upper limit and decided on the basis of the intended use of measurement results.

**Expanded measurement uncertainty** – Product of a combined standard measurement uncertainty and a factor larger than the number one.

**Coverage interval** - interval containing the set of true quantity values of a measurand with a stated probability, based on the information available.

**Coverage probability** – Probability that the set of true quantity values of a measurand is contained within a specified coverage interval.

**Coverage factor** – Number larger than one by which a combined standard measurement uncertainty is multiplied to obtain an expanded measurement uncertainty.

**Calibration** – Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication.

**Metrological traceability** - Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.

**Metrological traceability chain** - Sequence of measurement standards and calibrations that is used to relate a measurement result to a reference.

**Metrological traceability to a measurement unit** - Metrological traceability where the reference is the definition of a measurement unit through its practical realization.

**Verification** - Provision of objective evidence that a given item fulfils specified requirements.

**Validation** - Verification where the specified requirements are adequate for an intended use.

**Metrological comparability of measurement results (metrological comparability)** - Comparability of measurement results, for quantities of a given kind, that are metrologically traceable to the same reference.

**Metrological compatibility of measurement results (metrological compatibility)** - Property of a set of measurement results for a specified measurand, such that the absolute value of the difference of any pair of measured quantity values from two different measurement results is smaller than some chosen multiple of the standard measurement uncertainty of that difference.

**Measurement model** – Mathematical relation among all quantities known to be involved in a measurement.

**Measurement function** - Function of quantities, the value of which, when calculated using known quantity values for the input quantities in a measurement model, is a measured quantity value of the output quantity in the measurement model.

**Influence quantity** – Quantity that, in a direct measurement, does not affect the quantity that is actually measured, but affects the relation between the indication and the measurement result.

**Correction** - Compensation for an estimated systematic effect.

**Measuring instrument** – Device used for making measurements, alone or in conjuction with one or more supplementary devices.

**Accuracy class** –Cclass of measuring instruments or measuring systems that meet stated metrological requirements that are intended to keep measurement errors or uncertainties within specified limits under specified operating conditions.

**Measurement standard (etalon)** – Realization of the definition of a given quantity, with stated quantity value and associated measurement uncertainty, used as a reference.

**Conservation of a measurement standard** – Set of operations necessary to preserve the metrological properties of a measurement standard within stated limits.

**Calibrator** – Measurement standard used in calibration.