The word dictionary (unqualified) is usually understood to refer to a general purpose monolingual dictionary. There are other types of dictionaries that do not fit neatly into the above distinction, for instance bilingual (translation) dictionaries, dictionaries of synonyms ( thesauri), and rhyming dictionaries. In practice, the two approaches are used for both types. 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. 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. Specialized dictionaries include words in specialist fields, rather than a complete range of words in the language. Ī broad distinction is made between general and specialized dictionaries. It is a lexicographical reference that shows inter-relationships among the data. A dictionary is a listing of lexemes from the lexicon of one or more specific languages, often arranged alphabetically (or by radical and stroke for ideographic languages), which may include information on definitions, usage, etymologies, pronunciations, translation, etc.