Forum on Information Standards in Heritage (FISH) Thesauri

Historic England, as part of the Forum on Information Standards in Heritage (FISH), takes a leading role in setting standards for recording the built and buried heritage. By setting standards that can be adopted by everyone, we can make sure that all records are consistent. In other words, if everyone uses the same words to describe the same monument, archaeological object, building material, etc, then anyone using this common language can easily index, retrieve and understand these records. With this aim in mind, , Historic England and FISH are continually developing new thesauri to provide structure and guidelines for the standardisation of terms to be used when creating new records of the past.

Now, in our drive to disseminate these standards and promote their wider use, we are making available seven separate online thesauri. A tailor-made suite of programs has been developed, which uses a database to create a series of web pages for any chosen thesaurus. These can be easily accessed using a frames-capable browser and regularly updated as new terms are submitted and approved by our Data Standards Unit.

For more information about how a thesaurus works, click here how_to_icon.gif (822 bytes)  WIDTH=, otherwise go to the contents page, for instructions on how to use the site.

What is a thesaurus?

A thesaurus is a structured wordlist used to standardise terminology. It is used to assist in indexing and retrieving information within databases that make use of the same terminology.

Why is a thesaurus useful?

A thesaurus can set the standards for all information on a particular subject even when it is held in a number of data sets managed by different organisations.

A thesaurus:

  • allows terms, related by a similar subject, to be grouped into hierarchies and cross-referenced to other groups of terms which may be relevant to the subject.
  • provides the user with a single preferred term
  • allows terms to be selected at a general or specific level, depending on the level of indexing required.
  • is a dynamic tool, which can be developed by the addition, amendment and deletion of terms, relationships or hierarchies as dictated by individual needs.

How does a thesaurus work?

A thesaurus is primarily concerned with suggesting preferred terms for use in describing for example, types of monument, and establishing relationships between them.

There are three basic relationships within a thesaurus. These are:

  • the equivalence relationship
  • the hierarchical relationship
  • the associative relationship

as well as a scope note, which is used to define a term.

To create a thesaurus, these relationships are applied to each term.


The Equivalence relationship

This is the first relationship to be decided. A term can be ‘preferred’ or ‘non-preferred’; however, it is the preferred term that will be used in the hierarchies and for indexing.

A non-preferred term is a term that has the equivalent meaning to the preferred term but is not used for indexing. This might be because the term is:

  • a Synonym
  • a Quasi-Synonym
  • a Foreign Term
  • a Regional Term
  • an Archaic Term

The Hierarchical relationship

The second stage is to group the preferred terms into hierarchies. They are first gathered into conceptual groups, for example, all monuments that are barrows. Then within each conceptual group the terms are further divided into levels going from the broadest type of term to the narrowest and most specific type of term.

For example:

BARROW Conceptual group



Here the terms ROUND BARROW and BELL BARROW are both types of barrow, but BELL BARROW is a more specific form of ROUND BARROW and can therefore become a Narrower term of it.

A thesaurus can be poly-hierarchical; that is to say, a broad term can appear in more than one hierarchy and under more than one class.




FOG HORN appears in two hierarchies under two separate classes.

In the creation of hierarchies it is sometimes necessary to use a term to group monument types together; the grouping term itself however is not used for indexing. This is referred to as a non-index term and is identified in the attached alphabetical listings as an unemphasised, capitalised term (eg FOOD AND DRINK PROCESSING SITE) whilst an index term is identified as a bold, capitalised term (eg BREWHOUSE).

It is sometimes necessary to specify on what basis the terms have been grouped into a hierarchy. In these instances the broadest term of the hierarchy is given a facet indicator, whereby a term is further defined by an indication of its characteristics, for example: MONUMENT <BY FORM>

Terms with facet indicators are non-index terms.

The Associative relationship

Terms can be associated with each other but not necessarily connected by a hierarchy. This means that two terms similar in concept can be associated even though they come under different broad terms. These are referred to as ‘related terms’. Such terms are often used as an aid to help enquirers find terms similar to the initial term but which are not always immediately obvious.

For example: MANSIO


MANSIO is similar to INN and vice versa, so the related term should be looked at if the enquirer wants to broaden their original search.

Scope Notes

Scope notes are the final part to be added to a term. A scope note indicates exactly how the term is to be used in the context of the thesaurus. That is, it will provide a definition and any point that should be taken into consideration for the use of the term.

For example: VILLA

SN A term for a type of house, with varying definitions according to period. Roman villas were high-status and usually associated with a rural estate, whereas Georgian and later period villas were often semi-detached, town houses.

From the definition it is made clear that this is a building type and can be used to index villas of all periods, not just Roman.


Please note that these thesauri group terms by class rather than the broadest noun term (Top Term). It was felt it would be useful to group terms under CLASS schemes thereby linking monument types, building materials, etc, which are related thematically. For example, all places of worship, burial grounds, and funerary monuments are grouped under RELIGIOUS, RITUAL AND FUNERARY. Although the British standard includes the concept of class, the broadest noun term is the Top Term. These thesauri do not have Top Terms as the classes are not part of the hierarchy


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