WordWeb is a very useful and free English thesaurus and word dictionary. Check for word definitions and appropriate synonyms to slot in to passages when you cannot quite think of the right word to use. There are over 150,000 main words so it is unlikely that you won't find what you're looking for. However, it's also possible to access Wikipedia pages directly from the app as well for more extensive informative on a wealth of subjects to inform your own writing. Access to Wiktionary is also present to check more word references should you need it.

WordWeb Key Features:

• Look up words from the 150,000 root word dictionary
• Check for good synonyms with the thesaurus
• Access Wikipedia entries directly from the app
• Access Wiktionary entries for a more extensive dictionary

WordWeb is a word look-up tool for writers who want all their look ups in a single application.