[mourner]

For me as a non-native speaker who had this problem too, reading on Kindle helped learn the language immensely. You can long-press any word and it will show results from a high-quality dictionary (there are few to choose from, including the Oxford dictionary) — offline, and without putting the book away, which would be a deal breaker for me. It will also remember all the words you look up so that you can practice later.