New York Times, the famous new paper published in New York and distributed internationally has a nice feature on their web site. Readers of the articles on the NYT web site can double click on a word to lookup for word definition.
Here is the popup window displayed by NYT with definition when I double clicked the word Foe on one of their articles
To try this option, open the New York Times news article and double click on any of the words; you will see a popup window with definition of the double click word.
This is a very useful feature for people who don't have good command on English vocabulary