Hi Hitech
I would recommend ''Cambridge advanced learners dictionary". I've been using it for a while now, and it's very useful,
with a CD-ROM that contains recordings of every word in both British and Americanـــyou can also record your own pronunciation and then compare to either American or British+ smart thesaurus +interactive exercises including exam practice, I absolutely love it, I'm sure you will too ![Smile [:)]](/emoticons/emotion-1.gif)
* Merriam Webster dictionary is a very good one as well.
www.m-w.com
on second thought, since you're going to take the TOEFL test, maybe it'd be better if you choose Merriam Webster,,
because they're both American, the test and the Dictionary.
Good luck on your exams Hitesh!!