Depending on what type of phone you use, there may be a dictionary or translator app that works well. Play with the free ones first before you decide to spend money on a more advanced one. I can help you find one for your specific phone and language.
Here are some online dictionary tools:
M-W is one that I use often with students.
Dictionary.com lets you hear the word and offers definitions from many dictionaries, but the page is very cluttered.
Extra Credit!Look up the word cluttered! For 5 extra credit points, copy the definition into a comment here, and tell me which dictionary or website you used.