SFind for Spotify Premium - Pro app for iPhone and iPad

Features:
More than 182000 english definitions and large number of inflected forms
Fast as it works offline, internet is used only when a word is not found in the offline dictionary
You can leaf through words using your finger!
Easy and functional user interface, optimized also for tablets
Bookmarks and history with option to backup your bookmarks
Crossword help: the symbol ? can be used in place of unknown letter
Random search button (shuffle), useful to learn new words
Compatible with Moon+ Reader, FBReader and other applications via share button