1. Advanced English Dictionary and Thesaurus By Mobile Systems
The WordNet Dictionary and Thesaurus is a large lexical database of English with up to 140,000 entries and more than 1.4 million words, developed by the Cognitive Science Laboratory at Princeton University.
Instead of following the standard dictionary format, the WordNet dictionary is organized with an innovative and convenient approach. Nouns, verbs, adjectives and adverbs are grouped into sets of cognitive synonyms, interlinked by means of conceptual-semantic and lexical relations. In addition to the straightforward definition the dictionary shows how each word is linked to other words in terms of synonyms, opposites and similar words, but also hyponyms and hyperlinks within the group.
2. American Heritage® Dictionary — 4th Edition By Enfour, Inc.
This iPhone/iPod touch version has the entire 2,074 page, 7.5 pound dictionary with its nearly 300,000 terms –plus 64 thousand recorded sound files by native speakers– all available instantly at your fingertips.
More than 33,000 written examples, totaling 4,222,000 words, makes this largest mobile dictionary on ANY platform
The indexes alone are larger than most brand-name dictionaries. Even without the sound files, AHD4 would still be over 100MB and the largest dictionary in the AppStore.
3. Dictionary.com – Dictionary & Thesaurus – Free
The free Dictionary.com app delivers trusted reference content from Dictionary.com and Thesaurus.com. NO INTERNET CONNECTION IS NEEDED TO SEARCH WORDS. The app includes nearly 2,000,000 words, definitions, synonyms and antonyms. It also features audio pronunciation, voice-to-text search and Dictionary.com’s popular Word of the Day and Hot Word blog.
4. Dictionary! By Catlin Software, LLC
Dictionary! is an easy to use, no fluff dictionary app for your iPhone. Helps you find words when you need to without getting in your way.
5. Dream Dictionary for iPad By substatica
Dream Dictionary is the leading professional level dictionary of symbols which may appear in dreams as well as the potential meanings behind these symbols. With a database of thousands of definitions it maintains the most comprehensive collection available right at your fingertips. No internet connection required!
6. Dictionary for iPad By xyster.net
Dictionary is an intuitive, consistent, hyperlinked and integrated English illustrated dictionary and thesaurus, spell checker, vocabulary builder and Wikipedia browser. Dictionary’s intelligent word suggestion and search feature eliminates the need for a cluttered index interface.
Equally useful as a dictionary with intelligent word lookup, as a fast spell checker or as a Wikipedia web browser, Dictionary is fast and easy to use.
7. German English Dictionary & Translator By BitKnights LLC
German English Dictionary & Translator is an easy to use, user friendly dictionary, with a very big database (more than 280,000 translation pairs). No internet connection is required.
8. Italian English Dictionary & Translator By BitKnights LLC
Italian English Dictionary & Translator is an easy to use, user friendly dictionary, with a quite big database (more than 55,000 translation pairs). No internet connection is required.
9. Kotoba! (Japanese dictionary) By Pierre-Phi di Costanzo
This application is a multilingual Japanese dictionary for iPhone and iPod touch devices. The dictionary files are embedded in the application so that the dictionary service is available at all times with no additional cost.
Kotoba! was created using the amazing JMdict files from the Electronic Dictionary Research and Development Group based on the work of Jim Breen on the EDICT project.
10. Pleco Chinese Dictionary By Pleco Software
Pleco is the ultimate Chinese learning companion – an integrated Chinese dictionary / document reader / flashcard system with fullscreen handwriting input and live camera-based character recognition, from a company with over a decade of experience making mobile Chinese learning software.