Earlier this month, Google dropped Answers.com as their definitions provider. A month ago or so, Google would link from the word "definition" to Answers.com, now Google links to themselves.
For example, a search for [definitions] shows a hyperlink named "definition". Here is a picture:
When you click on it, it now takes you to Google Definitions at Google.com/Dictionary. In the past, and since early 2005 it took you to Answers.com.
I have not seen a thread or complain about this until today - so I guess most people didn't take much notice. The thread is at Google Web Search Help and it reads:
The "definition" feature Google has in its search page includes lots of features including comprehensive dictionary, pronunciation of words, translation to many other languages, all this gone, I have noticed its format was changed recently to a very simple uninformative format, very very disappointing! I was using it quite a lot.
Forum discussion at Google Web Search Help.