A
thesaurus is a work that lists words grouped
together according to similarity of meaning (containing
synonyms and sometimes
antonyms), in contrast to a
dictionary, which contains
definitions and
pronunciations. The largest thesaurus in the
world is the
Historical
Thesaurus of the Oxford English Dictionary, which contains more
than 920,000 words and meanings.
History and use of term
In antiquity,
Philo of Byblos
authored the first text that could now be called a thesaurus . In
Sanskrit, the
Amarakosha is a thesaurus in verse form, written
in the 4th century. The first example of the modern
genre,
Roget's
Thesaurus, was compiled in 1805 by
Peter Mark Roget, and published in 1852.
Entries in
Roget's Thesaurus are listed conceptually
rather than alphabetically.
Although including synonyms, 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.
The word "thesaurus" is derived from 16th-century
New Latin, in turn from
Latin
thesaurus, from
ancient Greek
thesauros, meaning a collection of things which are of big
importance or value (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.
Thesauri in IT
In
Information Science,
Library Science, and
Information Technology, specialized
thesauruses are designed for information retrieval. They are a type
of
controlled vocabulary, for
indexing or tagging purposes. Such a thesaurus can be used as the
basis of an index for online material. The
Art and Architecture
Thesaurus, for example, is used to index the Canadian national
database of museums, Artifacts Canada, held by the
Canadian Heritage
Information Network (CHIN).
Information retrieval thesauri are formally organized so that
existing relationships between concepts are made explicit. As a
result, they are more complex than simpler controlled vocabularies
such as authority lists and
synonym
rings. Each term is placed in context, allowing a user to
distinguish between "bureau" the office and "bureau" the furniture.
Following international standards, they are generally arranged
hierarchically by themes, topics or facets. Unlike a literary
thesaurus, these specialized thesauri typically focus on one
discipline, subject or field of study.
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.
Thesauri for information retrieval are typically constructed by
information specialists, and have their own unique vocabulary
defining different kinds of terms and relationships:
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) or
hyperonym is a more general term, e.g.
“Apparatus” is a generalization of “Computers”. Reciprocally, a
Narrower Term (NT) or hyponym 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 (meronyms and holonyms).
- 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". Unauthorized terms are often
called "entry vocabulary", "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). 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.
Literary Thesauri
- 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
- Historical Thesaurus
of English (HTE),
http://www.arts.gla.ac.uk/SESLL/EngLang/thesaur/toe1.htm
- WordNet
- OpenThesaurus
Specialized Thesauri for Information Retrieval
Standards and Manuals
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.
For multilingual vocabularies, the
ISO 5964 Guidelines for the
establishment and development of multilingual thesauri can be
applied.
Thesaurus Construction and Use: a practical manual. Jean Aitchison,
Allan Gilchrist and David Bawden. London and New York: Europa
Publications (2000).
See also
References
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