1- Vocab Genius
2- Vocabulary HD
This app helps students learn over 500 new words together with their pronunciation. Words are contextualized in examples making it easy for students to understand them. The app also provides synonyms, quizzes, and a pronunciation tool.
3- Dictionary
Dictionary is a powerful dictionary and thesaurus app that allows users to search for definitions of words from multiple trusted sources including: Webster's Dictionary, Roget's Thesaurus and The American Heritage Dictionary. The great thing about this app is that it works offline and provides translations of English into over 40 languages.
4- Dictionary by Wordiest (update: not working)
This is another wonderful dictionary app for language learners. It provides simple and easy to understand definitions of words. It also supports spell checking, fast searching and synonyms. The app also works offline.
5- Wordfolio (update: not working)
‘Wordfolio is a must-have app for any foreign language learner and a unique way to store all the foreign words you learn. Forget those "Vocabulary" notebooks that you bring to your language classes! Save all the new words to Wordfolio, and the app will help you memorize them as quickly as possible.’
6- Biscuit- Dictionary and Flashcards (update: not working)
This is a great vocabulary building app for language learners. It allows you to ‘create your own beautifully designed word list in seconds using simple gestures.It also lets you translate vocab from whatever you are reading and use study alerts or audio pronunciations to effortlessly review.’