Hello Jeremy Schomery since you have created this extension which is okay okay, i would suggest you to create or make another or imbibe into this feature of Google Dictionary (by Google) or dictionary which one can use while browsing or doing researches like me. Because while using chrome or chromium, this extension is useful but alas, while using firefox we dont have any such as this working as this great. So I hope you to create this here also or make another based on oxford or merriam webster. Thanks.

https://chrome.google.com/webstore/detail/google-dictionary-by-goog/mgijmajocgfcbeboacabfgobmjgjcoja