Super Power Dict mobile is an English English offline dictionary collects the best open dictionary sources for English with:
English English wiktionary 466.196 words: Wiktionary has grown beyond a standard dictionary and now includes a thesaurus a rhyme guide, phrase books, language statistics and extensive appendices. We aim to include not only the definition of a word, but also enough information to really understand it. Thus etymologies, pronunciations, sample quotations, synonyms, antonyms and translations are included.
Wordnet 150,000 words: a large lexical database of English. Nouns, verbs, adjectives and adverbs are grouped into sets of cognitive synonyms synsets, each expressing a distinct concept.
Real audio voice: wav pronunciation library 170 mb
The powerful of them can be compared with many famous English dictionaries like Oxford, Cambridge, Longman...
Wiktionary can edit and add words at wiktionary.org

Data please download manual because it is too big 168 mb
http:mspdict.googlecode.comfilesenglish.zip
Extract and copy mSPDict folder to primary memory sdcard folder, almost, this is memory card but some mobile like galaxy s, s2, lg optimus 2x... have internal memory, please copy mSPDict to internal memory because sdcard is internal memory path, and if mspdict alert have not data, please copy to all internal and sd card
Tools: convert data, clipboard manager, Mezzofanti
http:code.google.compmspdict
Features:
Suggestions
Data offline
Lookup many dicts without change
Spell check
History and favorite
TexttoSpeech add support build real voice mp3 and wav
showhide word mean
Tablet friendly
Lookup from reader softs like Moon reader, FBReader, Cool reader ... all softs support colordict
Portable, allinSD configuration
Support camera OCR textrecognition:
With Mezzofanti http:code.google.compmspdict
Or using cam dictionary in Google play Share via function with mSPDict 2.2 or above, check language: EnglishEnglish for offline mode.