Now by using new WordPress plugin by Juan Viñas you can create terms definitions and use them inside your posts and pages for displaying the definition of terms via jQuery.
Terms and Definitions Dictionary is the new WordPress plugin, it allows you to create a complete Dictionary on your WordPress based website. After activation it automatically defines a new post type showing up on admin sidebar as definitions with its own taxonomy and one more option Families (of Terms and Definitions). After creating definitions of your terms you can explain them to your blog readers when they hover over a particular term you have defines.
The plugin provides you various customization on its option page. You can edit color, size, movement, effects, autodetection etc. Now the question comes how you’ll be making a term (inside your blog post) to show its definition on mouseover. Its very easy, simply use these opening and closing shortcode tags [def] and [/def]. For example if you want to show definition of WordPress then use these tags like this: [def] WordPress [/def]
Even you can link your terms with other URLs showing the definition on mouseover at the same time. Suppose if you want to link WordPress to WordPress.Org and you also want that on mouseover it keeps showing the definition then in that case use the shortcode like this: [def url=’http://www.yoursite.com/]Term[/def] View FAQs if you have more questions.