Creating a rollover definition in your PDF

Creating a rollover glossary in a PDF
A customer asked me about the ability to use forms to create a rollover definition of words on a PDF page. Although you can do this with forms, another down-and-dirty way to create such a thing is with the Highlighter tool among the Comment and Markup tool set, and it’s easier.
First, select the Highlighter tool. Tools: Comment & Markup: Highlight text tool.
Next, highlight the word over which you want a rollover definition to appear when you hover your cursor over it. The default appearance will be yellow, 80% opaque. The trick is to reset the appearance of the highlight to 0% opaque.
Right (or control) click on the Highlight. In the Appearance tab of the Highlight properties dialog box, set the Opacity value to 0% and click OK.
With the Hand tool, double-click the now-invisible highlight and enter a definition for the word. You will see a small word balloon above the text to indicate that there is text there (there is no way to hide this).
Return to the properties (right or control click on the highlight) and choose Make properties default, so that the next time you create a highlight it will be invisible. Finally, click the Locked checkbox to prevent a user from editing the comment. If you need to protect the comment even further, you can use Security in Acrobat to restrict the permissions so that no one can change anything about the document—including comments.