Principles and rules of NPU terminology


Principles of NPU terminology are prerequisite of succesful communication between multiple parties.


All concepts are unambigous and traceable to well-defined, internationally agreed terminology or nomenclature

Principles of terminology

To reduce errors in communication, it is vital that the common terminology or nomenclature is agreed and understood by the sender and receiver.

Concept, definition, object and term

Terminology science distinguished between concept and term. The concept is an abstract idea that occurs in the mind, in speech, or in thought,but is assigned to a physical object, a definition and a term.Below example shows the close relations between the object, definition and term. The chemical, physical object has one definition and is designated as caffeine.


A concept has one definition that makes it possible to distinguish between different concepts that may have some common feature. An example is TSH receptor antibodies that are antibodies with distinc molecular and functional properties that may either activate, block or be function neutral. Their functional properties provide them with each distinc definition.


A concept can have many designated terms, however, to avoid confusion it is recommended to use only the preferred term or a prefered trivial name. Caffeine is the substance preferred trivial name but has a IUPAC name “1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl-“.

Another example is a measurement unit that can be expressed in several ways: The different expressions can be perceived as distinguished and different units, and may confuse health personnel with a potential risk of patient safety.

Unambigous concept

Concepts used in medical field should be unambigous, having only one definition. Concepts with two or more definitions are termed homonyms and exist in the common language. E.g. “book,” can mean “something to read” or “the act of making a reservation. These concepts can only be used in a specific context.

Agreed international terminology or nomenclature

Concepts that are defined by international terminology or nomenclature should mainly be used. International terminologies or nomenclatures in different scientifc fields have been established (see Medical and metrological vocabulary)


A NPU definition can be defragmented into individual concepts




Set of rules for the NPU terminology

International definitions

Concepts in the NPU terminology are defined by international medical and metrological vocabulary

  1. A unique NPU definition will never be deleted but can be disapproved due to unclear definition
  2. Terms (words) can be changed in a NPU definition if the concept is the same and only the terms have changed
  3. A new NPU definition needs to be established if a concept in the NPU definition has changed

Prefered terms

Prefered terms for the concepts should be used.

Note 1: Prefered terms can be changed by the international vocabulary, if the definition remain the same

Note 2: Technical names may be replaced by international decided trivial names, e.g. INN for medicine

Translation of terms

 Prefered terms may be translated to the national language by a national organization that is authorized to translate

National codes

  1. The same principles for the international definitions should be followed for national definitions (see Governance of International NPU codes)
  2. A national definition shall have the same syntax and structure as a NPU definition
  3. National concepts can be established if international concepts do not exist and if necessary