Dictionary.com is one of the best tools available for Android tablets.
The app keeps things really basic. Just type in the word you’re looking for, and if you’re not good at spelling, it predicts what you were trying to say and gives you a list of potential words. If you’re completely at a loss for how to spell a word, you can use the app’s voice feature to say it out loud. Dictionary.com understands both English and Spanish.
It also includes a thesaurus, synonyms and antonyms, a word of the day feature, and you can even see what commonly-searched words are trending.
The app has a very clean design and is easy to use. There’s the occasional ad or two, but they're pretty tiny. However, if that’s still too invasive for your liking, a full version of Dictionary.com is available for $1.99.