What is "metrology"

Metrology \Me*trol"o*gy\, n. [Gr. ? measure + -m['e]trologie.] The science of, or a system of, weights and measures; also, a treatise on the subject.

n. 1 (context uncountable English) The science of weights and measures or of measurement. 2 (context countable English) A system of weights and measures.

n. the scientific study of measurement

Metrology is the science of measurement and includes all theoretical and practical aspects of measurement.

Metrology is defined by the International Bureau of Weights and Measures (BIPM) as "the science of measurement, embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology."

The ontology and international vocabulary of metrology (VIM) is maintained by the Joint Committee for Guides in Metrology (JCGM), a group made up of eight international organisations – BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML, and ILAC.

Metrology is a very broad field and may be divided into three basic activities though there is considerable overlap between these activities:

• Definition of internationally accepted units of measurement
• Realisation of these units of measurement in practice
• Application of chains of traceability linking measurements made in practice to reference standards

Metrology also has three basic subfields, all of which make use of the three basic activities in varying proportions:

• Scientific or fundamental metrology
• Applied, technical or industrial metrology
• Legal metrology