OneLook.com: new favorite online dictionary
There are a gazillion online dictionaries out there today- Dicatonary.com, Merriam-Webster, UrbanDictionary.com- but my new favorite online dicationary is http://www.onelook.com.
With OneLook.com you can look up definitions to words in over 900 online dictionaries without any extra work. You can also translate words from and to English, pattern search (crosswords, anyone?), and (probably my favorite feature) look up words by their concepts!!