Enter a question or calculation and Wolfram|Alpha uses its built-in algorithms and data to get the answer. A huge set of information and tons of models, methods, and algorithms that make it possible to compute whatever can be computed about anything

Internet dictionary of slang words and phrases. More than 5 million street lingo words and expressions have been defined by the Internet community. The definitions on Urban Dictionary are meant to be those of slang or subculture words, phrases, and phenomena not found in standard dictionaries and tend to have the newest words. Entries are checked by volunteer editors and rated by site visitor…

Look in hundreds of general and specialized dictionaries at once. Great for obscure words or when you want to compare different dictionaries

Look up your word in this authoritative Merriam-Webster Online Dictionary, with more than 215,000 definitions with pronunciations

Translate text from English into Spanish, French, German, Italian, Dutch, Portuguese, Russian, Norwegian, Simplified Chinese, Traditional Chinese, Japanese or the other way around

Quickly find synonyms, antonyms, and related words with Thesaurus.com. Find words that mean the same (synonyms) in synonym dictionary and mean the opposite (antonym) in the antonym dictionary, with this free online thesaurus

Get definitions for computer-related terminology from the Free On-Line Dictionary Of Computing

Wordsmyth's dictionary contains 50,000 headwords, and very precisely defined and hyperlinked synonyms

Look up any word in Dictionary.com's meta dictionary

Find the meaning of any legal term

VoyCabulary makes the words on any webpage into links so you can look them up in a dictionary or other word reference tool by clicking on the words.

Get definitions for Internet, hardware, software or networking-related terminology

Free lexical database of the English language, complete with meanings, etymologies, and pronunciations.

The LOGOS New Dictionary translates words to and from most languages, including: English, French, Italian, Brazilian Portuguese, Portuguese, Spanish, Catalan, Basque, Galician, Japanese, Chinese, Traditional Chinese, Dutch, Greek, Polish, Russian, Danish, Swedish, Arabic, Persian and 168 more!