Thesaurus

A thesaurus is a book that contains synonyms and sometimes antonyms, in contrast to a dictionary, which contains definitions and pronunciations.

The first example of this genre, "Roget's Thesaurus", was compiled in 1805 by Peter Roget, and published in 1852. Entries in "Roget's Thesaurus" are listed conceptually rather than alphabetically.

Although including synonyms, entries in a thesaurus should not be taken as a complete list of all the synonyms for a particular word. The entries are also designed for drawing distinctions between similar words and assisting in choosing exactly the right word. Unlike a dictionary, a thesaurus entry does not define words.

In information technology, a thesaurus represents a database or list of semantically orthogonal topical search keys. In the field of Artificial Intelligence, a thesaurus may sometimes be referred to as an ontology.

Thesaurus databases, created by international standards, are generally arranged hierarchically by themes and topics. Such a thesaurus places each term in context, allowing a user to distinguish between "bureau" the office and "bureau" the furniture. A thesaurus of this type is often used as the basis of an index for online material. The Art and Architecture Thesaurus, for example, is used to index the national databases of museums, Artifacts Canada, held by the Canadian Heritage Information Network (CHIN).

Etymology

The word "thesaurus" is derived from 16th-century New Latin, in turn from Latin "thesaurus", from ancient Greek "polytonic|θησαυρός" "thesauros", meaning "storehouse" or "treasury" (and thus the medieval rank of thesaurer was a synonym for treasurer). This meaning has been largely supplanted by Roget's usage of the term.

Definition

A formal definition of a thesaurus designed for indexing and information retrieval is:

* a list of every important term (single-word or multi-word) in a given domain of knowledge; and
* a set of related terms for each term in the list.

As such, it is a list of subject headings and cross-references used in the filing and retrieval of documents.
Terms are the basic semantic units for conveying concepts. They are usually single-word nouns, since nouns are the most concrete part of speech. Verbs can be converted to nouns – "cleans" to "cleaning", "reads" to "reading", and so on. Adjectives and adverbs, however, seldom convey any meaning useful for indexing. When a term is ambiguous, a “scope note” can be added to ensure consistency, and give direction on how to interpret the term. Not every term needs a scope note, but their presence is of considerable help in using a thesaurus correctly and reaching a correct understanding of the given field of knowledge.

"Term relationships" are links between terms. These relationships can be divided into three types: hierarchical, equivalency or associative.

"Hierarchical" relationships are used to indicate terms which are narrower and broader in scope. A "Broader Term" (BT) is a more general term, e.g. “Apparatus” is a generalization of “Computers”. Reciprocally, a Narrower Term (NT) is a more specific term, e.g. “Digital Computer” is a specialization of “Computer”. BT and NT are reciprocals; a broader term necessarily implies at least one other term which is narrower. BT and NT are used to indicate class relationships, as well as part-whole relationships.

The "equivalency" relationship is used primarily to connect synonyms and near-synonyms. Use (USE) and Used For (UF) indicators are used when an authorized term is to be used for another, unauthorized, term; for example, the entry for the authorized term "Frequency" could have the indicator "UF Pitch". Reciprocally, the entry for the unauthorized term "Pitch" would have the indicator "USE Frequency". Used For (UF) terms are often called "entry points", "lead-in terms", or "non-preferred terms", pointing to the authorized term (also referred to as the Preferred Term or Descriptor) that has been chosen to stand for the concept. As such, their presence in text can be use by automated indexing software to suggest the Preferred Term being used as an Indexing Term.

"Associative" relationships are used to connect two related terms whose relationship is neither hierarchical nor equivalent. This relationship is described by the indicator "Related Term" (RT). The way the term "Cybernetics" is related to the term "Computers" is an example of such a relationship. Associative relationships should be applied with caution, since excessive use of RTs will reduce specificity in searches. Consider the following: if the typical user is searching with term "A", would they also want resources tagged with term "B"? If the answer is no, then an associative relationship should not be established.

Examples

* "Thesaurus of English Words & Phrases" (ed. P. Roget); ISBN 0-06-272037-6, see: Roget's Thesaurus.
* "The Synonym Finder" (ed. J. I. Rodale); ISBN 0-87857-236-8
* "Webster's New World Thesaurus" (ed. C. Laird); ISBN 0-671-51983-2
* "Oxford American Desk Thesaurus" (ed. C. Lindberg); ISBN 0-19-512674-2
* "Random House Word Menu" by Stephen Glazier; ISBN 0-679-40030-3, a blend of thesaurus, dictionary, and glossary.

An important thesaurus project of recent years is the Historical Thesaurus of English (HTE), currently in progress at the University of Glasgow. The HTE, which started in 1964, will be a complete database of all the words in the second edition of the Oxford English Dictionary, arranged by semantic field and date. In this way, the HTE arranges the whole vocabulary of English from the earliest written records (in Anglo-Saxon) to the present alongside types and dates of use. As a historical thesaurus, it will be the first for any of the world's languages. The HTE project has already produced the Thesaurus of Old English [ [http://www.oenewsletter.org/OEN/reports.php/kay38_3/ Old English Newsletter Online ] ] , which is derived from the whole HTE database. [The HTE database is freely available at http://www.arts.gla.ac.uk/SESLL/EngLang/thesaur/toe1.htm here]

Specialized

* "NAL Agricultural Thesaurus", (United States National Agricultural Library, United States Department of Agriculture)
* "European Thesaurus on International Relations and Area Studies"; ISBN 978-3-927674-11-0
* "Evaluation Thesaurus" (by. M. Scriven); ISBN 0-8039-4364-4
* "Great Song Thesaurus" (by R. Lax & F. Smith); ISBN 0-19-505408-3
* "Thesaurus of Psychological Index Terms" (APA); ISBN 1-55798-775-0
* "Clinician's Thesaurus", (by E.Zuckerman); ISBN 1-57230-569-X
* "Art and Architecture Thesaurus", (Getty Institute)
* "AGROVOC Thesaurus", (Food and Agriculture Organization of the United Nations)
* " GEneral Multilingual Environmental Thesaurus", (European Environment Agency)

Standards

The "ANSI/NISO Z39.19 Standard" of 2005 defines guidelines and conventions for the format, construction, testing, maintenance, and management of monolingual controlled vocabularies including lists, synonym rings, taxonomies, and thesauruses. [ [http://www.niso.org/kfile_download?pt=RkGKiXzW643YeUaYUqZ1BFwDhIG4-24RJbcZBWg8uE4vWdpZsJDs4RjLz0t90_d5_ymGsj_IKVaGZww13HuDlXTWtluYrc77y9xWOHiF7M8%3D ANSI/NISO Z39.19 - 2005 Guidelines for the Construction, Format and Management of Monolingual Controlled Vocabularies] , ISBN 1-880124-65-3.]

For multilingual vocabularies, the "ISO 5964 Guidelines for the establishment and development of multilingual thesauruses" can be applied.

See also

* Controlled vocabulary
* Dictionary
* Ontology (computer science)
* Simple Knowledge Organisation System
* WordNet

References

External links

* [http://www.synonyms.me/ Synonyms and Definitions at Synonyms.Me] - Your online synonyms and definitions finder!
* [http://tematres.r020.com.ar/index.en.html TemaTres: open source thesaurus management]
* [http://www.cs.utexas.edu/users/jared/aiksaurus/ Aiksaurus: open source and online thesaurus]
* [http://education.yahoo.com/reference/thesaurus/category_index Yahoo!Education: Thesaurus] One of the few examples of the old-style categorical listings available online.
* [http://thesaurus.publicdomaindb.org/ Public Domain Db's Free Online Thesaurus] Large thesaurus with over 30,000 words indexed.