http://www.mobilerated.com/dir/Application/1224/Easywords.html
This application was originally developed to help GRE test taker learn new words for the verbal section. It includes a searchable list of about 1200 common GRE words and their explanation, and a game to practice these words.
It is well suited not only for GRE preparation, but to learn difficult English words in an interaцtive and pleasant way using the mobile device. Last but not least it comes in handy as a dictionary since you don’t need to search for common words anyway.