A
dictionary (also called a
wordstock,
word reference,
wordbook,
lexicon, or
vocabulary) is a collection of
words in one or more specific
languages, often listed
alphabetically (or by
radical and stroke for
ideographic languages), with usage information,
definitions,
etymologies,
phonetics,
pronunciations, and other information; or a book of words in one language with their equivalents in another, also known as a
lexicon. According to
Nielsen (2008) a dictionary may be regarded as a
lexicographical product that is characterised by three significant features: (1) it has been prepared for one or more functions; (2) it contains data that have been selected for the purpose of fulfilling those functions; and (3) its lexicographic structures link and establish relationships between the data so that they can meet the needs of users and fulfill the functions of the dictionary.
A broad distinction is made between general and
specialized dictionaries. Specialized dictionaries do not contain information about words that are used in language for general purposes—words used by ordinary people in everyday situations. Lexical items that describe concepts in specific fields are usually called terms instead of words, although there is no consensus whether
lexicology and
terminology are two different fields of study. In theory, general dictionaries are supposed to be
semasiological, mapping word to
definition, while specialized dictionaries are supposed to be
onomasiological, first identifying
concepts and then establishing the terms used to designate them. In practice, the two approaches are used for both types. There are other types of dictionaries that don't fit neatly in the above distinction, for instance
bilingual (translation) dictionaries, dictionaries of
synonyms (
thesauri), or
rhyming dictionaries. The word dictionary (unqualified) is usually understood to refer to a monolingual general-purpose dictionary.
A different dimension on which dictionaries (usually just general-purpose ones) are sometimes distinguished is whether they are
prescriptive or descriptive, the latter being in theory largely based on
linguistic corpus studies—this is the case of most modern dictionaries. However, this distinction cannot be upheld in the strictest sense. The choice of
headwords is considered itself of prescriptive nature; for instance, dictionaries avoid having too many taboo words in that position. Stylistic indications (e.g. ‘informal’ or ‘vulgar’) present in many modern dictionaries is considered less than objectively descriptive as well.
Although the first recorded dictionaries date back to Sumerian times (these were bilingual dictionaries), the systematic study of dictionaries as objects of scientific interest themselves is a 20th-century enterprise, called
lexicography, and largely initiated by
Ladislav Zgusta. The birth of the new discipline was not without controversy, the practical dictionary-makers being sometimes accused of "astonishing" lack of method and critical-self reflection.