A dictionary is a reference work that contains an alphabetical list of words, their definitions, and other information related to them. It is used to look up the meanings of words, names, and terms. Dictionaries are also used to find synonyms and antonyms as well as to understand the history and usage of words. Dictionaries typically contain entries for each word or phrase which includes its meaning(s), etymology (origin), usage (grammatical rules), pronunciation, part of speech, variants, related terms, and examples. They may also include illustrations or photos. Additionally, some dictionaries provide additional information such as slang or colloquial usages, foreign translations, synonyms/antonyms/homophones/homographs/hypernyms/hyponyms/meronyms/holonyms, etymologies (history of the word), proverbs and sayings associated with the word(s) in question. The primary purpose of a dictionary is to provide accurate information about the words it contains so that people can use them correctly in speech and writing. A good dictionary should be comprehensive yet concise; it should contain up-to-date information; it should be easy to navigate; it should be authoritative; it should be reliable; and it should be free from bias or prejudice.