mouse over pop-up that explains terminology

I’m sure this must exist. I am writing a graphic design website that uses lots of native terminology – such as eps file, cmyk, pantone etc which are all familiar to us but not to our clients. I would like a plugin that gives the visitor the chance to mouse over or click the word to receive an explanation.
Even better they could click a readmore link and go to a bookmark on a page of faq’s in alphabetical order, but I don’t want them to have to scroll down as it could be a long page. In an ideal world the read more link would take them straight down the page to the listing…

I don’t really know what to search for on plugins.

Simon