A dictionary is a book of alphabetically listed words in a specific language, with definitions, etymologies, pronunciations, and other information;Webster's New World College Dictionary, Fourth Edition, 2002 or a book of alphabetically listed words in one language with their equivalents in another, also known as a lexicon.

In many languages, words can appear in many different forms, but only the undeclined or unconjugated form appears as the headword in most dictionaries. Dictionaries are most commonly found in the form of a book, but some newer dictionaries, like StarDict and the New Oxford American Dictionary are dictionary software running on PDAs or computers. There are also many online dictionaries accessible via the Internet.

History

The oldest known dictionaries were Akkadian empire cuneiform tablets with bilingual Sumerian-Akkadian wordlists, discovered in Ebla (modern Syria) and dating roughly 2300 BCE.[http://encarta.msn.com/encyclopedia_761573731/Dictionary.html#p3 Dictionary - MSN Encarta ] The early 2nd millennium BCE Urra=hubullu glossary is the canonical Babylonian version of such bilingual Sumerian wordlists. A Chinese dictionary, the ca. 3rd century BCE Erya, was the earliest monolingual dictionary, although some sources cite the ca. 800 BCE Shizhoupian as a "dictionary", modern scholarship considers it a calligraphic compendium of Chinese characters from Zhou dynasty bronzes. Apollonius the Sophist (fl. 1st century CE) wrote the oldest extant Greek lexicon, which lists Homeric vocabulary and meanings. According to the Nihon Shoki, the first Japanese dictionary was the long-lost 682 CE Niina glossary of Chinese characters. The oldest existing Japanese dictionary, the ca. 835 CE Tenrei Banshō Meigi, was also a glossary of written Chinese.

Arabic dictionaries were compiled between the 8th and 14th centuries CE, organizing words in rhyme order (by the last syllable), by alphabetical order of the radicals, or according to the alphabetical order of the first letter (the system used in modern European language dictionaries). The modern system was mainly used in specialist dictionaries, such as those of terms from the Qur'an and hadith, while most general use dictionaries, such as the Lisan al-`Arab (13th c., still the best-known large-scale dictionary of Arabic) and al-Qamus al-Muhit (14th c.) listed words in the alphabetical order of the radicals. The Qamus al-Muhit is the first handy dictionary in Arabic, which includes only words and their definitions, eliminating the supporting examples used in such dictionaries as the Lisan and the Oxford English Dictionary.