The Online Encyclopedia and Dictionary







The word thesaurus is New Latin for treasure; coined in the early 1820s. Besides its meaning as a treasury or storehouse, it more commonly means a listing of words with similar or related meanings. For example, a book of jargon for a specialized field; or more generally a list of subject headings and cross-references used in the filing and retrieval of documents. (Or indeed papers, certificates, letters, cards, records, texts, files, articles, essays and perhaps even manuscripts.)

The first example of this genre, Roget's Thesaurus, was published in 1852, having been compiled earlier, in 1805, by Peter Roget. Entries in Roget's Thesaurus are listed alphabetically and are a great resource for writers.

Although including synonyms, entries in a thesaurus should not be taken as a list of synonyms. The entries are also designed for drawing distinctions between similar words and assisting in choosing exactly the right word. Nor does a thesaurus entry define words. That work is left to the dictionary.

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, Artefacts Canada, held by the Canadian Heritage Information Network (CHIN).

Formal Definition

A formal definition of a thesaurus, is:

  • (1) a precompiled list of important words in a given domain of knowledge and
  • (2) for each word in the list, a set of related words.

Identified here are the two main parts of the Thesaurus; index terms (1) and term relationships (2). The index terms are the individual words, terms, or phrases. These are the basic semantic unit for conveying ideas. The terms are usually single-word nouns, since nouns are the most concrete part of speech. Adjectives and adverbs seldom convey any useful meaning, while verbs can be converted into nouns; cleaning, reading and so on. When terms are ambiguous, a “scope note” can be added to ensure consistency, give directions how to interpret the term. Naturally, 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.

The term relationships are links between the terms, often describing hierarchical relations, or synonyms and near-synonyms. Synonyms, and other useful relationships between terms, are called related terms (RT). The way the term Cybernetics is related to computers is an example of these relationships. Hierarchical relationships are used to narrow or broaden the scope of a term. Broader Terms (BT) generalizes a term, i.e. “Apparatus” is a generalization of “Computers”. Reciprocally, Narrower Terms (NT) is a specialization, i.e. “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.



External Links

See also: Dictionary

Last updated: 05-13-2005 07:56:04