if you go to Google.com and type in a word, when the search comes up, you can ignore it and just look in the blue bar at the top.
There you will see the word in white text and it will be underlines - it is a link to that word on dictionary.com
Clicking on it will give you like 8 different definitions and usages of the word from various published dictionaries.
Google is also a good thing to use as a spell checker - although I obviously don't use it frequently enough.