A dictionary is a list of words with their definitions, a list of characters with its glyph or a list of words with corresponding words in other languages. Many dictionaries also provide pronunciation information, word derivations, histories, or etymologies, illustrations, usage guidance, and examples in sentences.
Dictionaries of alphabetic languages list words in alphabetical order. With non-alphabetic languages, it may be different. The order in a dictionary with ideographic entries such as Chinese character is often troublesome and controversial because each character has different readings. Collation systems for logographs do exist. In Japanese and Korean, words containing Chinese characters (called Kanji in Japanese and Hanja in Korean) can be spelled in Hiragana and Hangul respectively, and so are inserted in their proper alphabetical order in dictionaries, alongside words not derived from Chinese characters. Furthermore, in entries for words derived from characters, the main entry words are spelled in Hiragana (for Japanese dictionaries) and Hangul (for Korean dictionaries), with the Chinese characters inserted in parentheses after each entry word.
Another variant is the glossary, an alphabetical list of defined terms in a specialized field, such as medicine or science. The simplest dictionary, a defining dictionary, provides a core glossary of the simplest meanings of the simplest concepts. From these, other concepts can be explained and defined, in particular for those who are first learning a language. In English the commercial defining dictionaries typically include only one or two meanings of under 2000 words. With these, the rest of English, and even the 4000 most common English idioms and metaphors, can be defined.
Most modern dictionaries are descriptive, although many, such as the American Heritage dictionaries make extensive efforts to provide information on the best usage, and almost all dictionaries provide some information on words considered erroneous, vulgar, or easily confused. In any case, in the long run, usage alone determines the meaning of words, although dictionaries provide conservative continuity, even the most descriptive.
Noah Webster's dictionary was published by the G&C Merriam Company of Springfield, Massachusetts which still publishes Merriam-Webster dictionaries, but the term Webster's is considered generic and can be used by any dictionary.
Picture Dictionary Online Picture Dictionary with search function. Uses pictures and symbols from Universal Picture Language. Grasp the meaning of a word with just a glance at its representative picture.
Open Dictionary Offers various definitions, translations and pronunciations in many languages (uses Wiktionary and WordNet for most of its entries).
An open content dictionary project is the GNU Collaborative International Dictionary of English (GCIDE). This dictionary uses Webster's Revised Unabridged Dictionary (1913) and WordNet as its sources and is being developed collaboratively under the terms of the GNU General Public License. It describes itself as "a freely-available set of ASCII files containing the marked-up text of a substantial English dictionary".
Bartleby.com Online publication of The American Heritage Dictionary, Fourth Edition. Featuring 70,000 audio word pronunciations, 900 full-page illustrations and over 10,000 new words and senses. http://www.bartleby.com/61/
AskOxford.com For questions on English grammar, spelling, and usage; to search a dictionary of words, names or quotations; for help with writing; for crosswords and puzzles. http://www.askoxford.com/
The Rap Dictionary Hip-hop slang and also contains a list of hip-hop artists and their real names. http://www.rapdict.org/terms/a
Ultralingua Online Dictionary Searchable dictionary of the English language, with standard, reverse and phonetic lookup. Also links to a range of other language resources. http://www.ultralingua.net/
HyperDic Based on the WordNet lexical database and thesaurus, this dictionary covers only a selection of the most frequent English words. Includes synonyms, antonyms, examples and pronunciation, and links between related words. http://www.hyperdic.net/
The Beet Foundation General purpose online English language dictionary and Thesaurus. http://beetfoundation.com/words/
Macmillan English Dictionary Resource site for the new Macmillan English Dictionary. http://www.macmillandictionary.com/
DataSegment.com: Online Dictionary Find definitions by alphabetical browsing or word lookup. Powered by several print dictionaries. http://onlinedictionary.datasegment.com/
The Wordsworth Compendium Program containing over 516,000 English words and phrases to solve word puzzles. Useful for the search and manipulation of words in all aspects of logological activities. http://dictionary-thesaurus.com/
Dictionary.com Online English dictionary, thesaurus and reference guide. Includes word games, online translator, and word of the day feature. http://dictionary.reference.com/
Die.net Online Dictionary Cross-referenced definitions, spelling correction, and searches from WordNet, Webster's, and a variety of specialized sources. Supports regular expressions and the DICT protocol. http://dict.die.net/
AnsMe.com Dictionary Finds definitions, similar-sounding words, relations, words that rhyme, and translations. http://dictionary.ansme.com/
SmartDictionary.com Supports both searching and browsing and encourages user contributions. http://www.smartdictionary.com/
Freeseach Dictionary A British English dictionary powered by the Cambridge University Press that contains around 150,000 words. The site offers a search feature or can be browsed by letter. http://www.freesearch.co.uk/dictionary
dictionary.net Comprehensive dictionary database of word and phrase definitions from 8 different sources. http://www.dictionary.net/
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