dictionary 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. 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 studiesâ€"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. †informalâ€^TM or †vulgarâ€^TM) 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. An OSH glossary used in safety and health at work which is, adopted by ILO