This simple extension for Wikipedia, that you can install in your browser's sidebar or to the main page of the website, will let you get a quick description or definition of a term that may not be familiar to you. The only thing that you need to do is to hover the cursor over the link that interests you, and you'll get a definition in a pop-up window.

But there is more! The definition will be displayed as long as you hover the cursor, and images will zoom in and out when you're scrolling. And there are no limits! The definition will be shown even if the text is not long enough to fit in a single line.