So far really good. When needing a quick definition, I would often have to open a tab for a specific website. I can get that from Definer.
One main issue is that you can use either the dictionary OR the translator, not both at the same time.
As a non-English speaker, I'd rather search for the English definition AND get the translation in my mother tongue if needed.
Please, add a tab to access the translation from a definition, and conversely.

Maybe also add links to the thesaurus?

I do like the custom source feature with dynamic fields! I was able to easily add the Meriam Webster dictionary or Thesaurus. If we could create several custom sources (with different custom icons), that would be great. I could expand on the capabilities of a great tool!