Earlier in April this year, Google added a new search options in the sidebar "dictionary," a new interface for Google Dictionary that combines definitions from a reputable dictionary with definitions from the Web, usage examples and other useful information.
Now, some users reported that Google's define: operator no longer works. The operator was useful to find definitions obtained from Web pages, so you could type [define:iffy] and find a list of definitions. Now the operator is no longer broken, but it only shows the definition from Google Dictionary and links to the dictionary page. You could type [define iffy] and get similar results.