I made a simple plugin that I would like to share:
This plugin simplifies for your readers and you by making it easy to define terms or abbreviations that needs an explanation. Define a common dictionary of terms and their definition in a YAML file. Then inside markdown files you can use the provided glossary liquid tag to insert a tooltip for a defined word from the dictionary. The tooltip will show the term definition on mouse hover.
and feel free to contribute to make it better!