I'd say that the text is still reasonably short and not like "one would find in a dictionary.".
I understand the Wiki as "keep it short, OSM is not the right place to give a full description like on a Wikipedia page". That would also include not circumventing this limitation by moving a long explanation to another tag.   

But looking at it for a second time, I'd say that the part in parentheses should go to source:name:etymology.