Ninja Words claims to be 'A really fast dictionary... fast like a ninja.'
However, it's not the speed that is interesting, but the ability to generate word lists very quickly. Let's say that you want to get the definition of 'geography' but without using the search function, you can just type the following in the address bar:
So far so good? Now to generate a list of definitions, we just need to add commas. Try this link:
So you could use this to generate a word list, copy, paste and print it out or pass the link on to students. Don't forget to use a service like http://bit.ly if you need to shorten it.