Hi Edvind! 

I think the solution is could be either simple or less simple.  Is the dictionary/database in CMS? Is it language specific?

So you could either inject a "html template"  with a parameter name that on the live page being replaced by javascript depending of the parameter. 

Altenate solution would be to create a selector or search what fetches that pair of definition/explanation using internal api controller and inject into tinymce. You would perhaps need a language parameter here too. Drawback here would be not being able to edit the injected definition in a good way.

Hi JOnas,

Thank you for your answer. 
The dictionary does not exist yet, but should be maintained by the editors in the CMS. We operate with only one language.
I'm not entirely sure how to make it, a dictionary list with the word itself as key maybe. Ideally i would want a plugin where you can select an explanation. You could have two explanations for the same word for different contexts. 

I have been thinking the same as what you suggest in your "alternate solution". Drawback is that you can have only one definition if it is fetched based on a key that is the word itself. 

Didnt understand what you meant by injecting a "html template" with a parameter name though :) 

As for the plugin itself, I didn't find anything on the big internet, so Im trying to write my own plugin. I'm struggling with few or none good examples though. The examples i found are like 7 years old or older, and not compatible with the newest tinymce. My hopes were that someone else had encountered this exact problem and shared the implementation somewhere :)

// Eivind