Thesaurus

From Wikipedia, the free encyclopedia

For the American rapper, see TheSaurus (rapper).

A thesaurus is similar to a dictionary, but instead of definitions and pronunciations, it contains synonyms and antonyms.

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 and antonyms, entries in a thesaurus should not be taken as a list of them. 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).

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[edit] Etymology

The word "thesaurus" is derived from 16th-century New Latin, in turn from Latin thesaurus, from ancient Greek 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.

[edit] Definition

A formal definition of a thesaurus designed for indexing 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.

A miniature standard English thesaurus combined with a dictionary
A miniature standard English thesaurus combined with a dictionary

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. Thesaurus designers are generally careful to ensure that BT and NT indicate class relationships, as distinguished from 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" into the thesaurus, "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.

[edit] Examples

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[1], which is derived from the whole HTE database.[2].

[edit] Specialized

[edit] 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 thesauri.[3]

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

[edit] See also

Look up thesaurus in
Wiktionary, the free dictionary.

[edit] References

  1. ^ Old English Newsletter Online
  2. ^ The HTE database is freely available at http://www.arts.gla.ac.uk/SESLL/EngLang/thesaur/toe1.htm here
  3. ^ ANSI/NISO Z39.19 - 2005 Guidelines for the Construction, Format and Management of Monolingual Controlled Vocabularies, ISBN: 1-880124-65-3.

[edit] External links