A free program for Android, by MobiSystems.

Audio Collins is one of the most established names when it comes to languages and reference dictionaries. This app, in particular, is determined to provide you with the most accurate audio pronunciation guide, word-for-word translations, and reference materials for English and Vietnamese languages. This dictionary’s extensive word-for-word translations and reference materials are available in text and audio formats.

If you are a student, you can easily search through thousands of words and get the definition, synonyms, and example sentences. If you are a teacher or a student who wants to improve his or her vocabulary, you can search by word, synonyms, and example sentences to find the word in different forms and expressions.