Free Dictionary Org is an English dictionary app that offers a comprehensive list of English definitions, synonyms, pronunciation, and spelling. It is a free app and has been chosen as the "Best Dictionary App" by O'Reilly Media's book "Best Android Apps: The Guide for Discriminating Downloaders."

One of the most useful features of Free Dictionary Org is its auto-suggestion feature, which suggests words as you type. Additionally, the app has an offline database dictionary query that allows you to search for words even when there is no network. The app also has Wikipedia integration, which provides more information about the searched word.

Free Dictionary Org also has a quiz game that helps you learn new words and enhance your vocabulary. The app also has the option to search for the word on Google Images, which can be helpful when you need to understand the meaning of a word better. Lastly, the app keeps a search history of the words you have looked up, making it easy to revisit them later.

Overall, Free Dictionary Org is an excellent English dictionary app for Android that provides numerous features to enhance your vocabulary and understanding of the English language.