LookUp: An elegant dictionary ($2.99) by Rajesh Bhargava is a handy tool that can be used for finding out much more than the definition of a word. Since Apple introduced a built-in dictionary to iOS, the need for dictionary apps has dwindled, especially since I can ever-so-quickly find a definition using Launch Center Pro, which is what I've stuck to these days. To be useful, any modern dictionary app needs to make word lookup quick, elegant, and, ultimately, provide more than just a definition. LookUp definitely fits these criteria, and for this reason, could very well become your main iPhone dictionary.
The app isn't at all difficult to navigate around. Upon opening it, you'll be presented with the word of the day for the current day, and by swiping the cards, you can view the previous days' choices. You can begin using the search field, which, before typing anything in, allows access to your history of words looked up and starred entries. After typing something in, you'll be presented with what is sometimes only one type of result, but other times, multiple cards will be available about the particular word or phrase you're inquiring about.
Cards presented can include the definition, synonyms, the etymology of the word, and even the word or phrase's Wikipedia page. The right cards are usually provided, however, sometimes I found some results to be missing. For example, typing in “iPhone” only presents a definition card, when iPhone obviously has its own Wikipedia page.
Although plain old dictionary apps that provide only definitions of words have become useless nowadays, those that provide a little more still have a strong purpose, and LookUp is definitely one of these. The simple UI doesn't get in the way, and the app allows for super quick word lookup that provides extra information from definitions and synonyms to a word or phrase's etymology and Wikipedia entry. For this reason, it could definitely be worth the $2.99 download. You can find the iPhone-optimized Lookup: An elegant dictionary on the App Store here.