A very good one, with the exception of a few disadvantages like limited vocabulary

if you could just please add some custom searches to it, and also please more than one language at the time (see definer ext) , this would be perfect, definer is good but its HUGE for almost same thing, I love tiny extensions that are actually useful like this one. please also add ability to disable bubble on some sites or make it smaller or appear on a fixed location (like following mouse cursor so you can take the bubble out of the way of the text you are reading) use some other way to show result.

Works very well. Sadly it doesn't work in instance where Google can't find the definition in its dictionary.

If I could use this with selected words. sometimes I struggle to understand idioms.

wish there was a dark theme

Great, simpledictionary (though would really love more languages added, like Arabic). Besides the language limitations, my only quibble is one that has been mentioned: popups shouldn't occur in edit fields. Double clicking on a word to retype it brings up the popup and obscures the text.

It used to be perfect, one day the dictionary stopped working and says no definition found.

I would like to be able to set the engine to duckduckgo (&/or others) instead of google

I really wish they added a popup where I can manually enter a word and check the definition. I had to go to google to check the definition

For what it is, it works well. That being said, I decided to uninstall it for a few reasons...

1. Apparently, all the definitions are taken from a Google search. Granted the definitions themselves are fine, but it would be nice to have a larger pool of sources to choose from like Merriam-Webster or DuckDuckGo. Defaulting to Google works I suppose, but I don't think a Dictionary extension needs Google.

2. On that note, I can basically recreate the functionality of this extension using Swift Search Selection by adding a source like Miriam-Webster as a search engine, to say nothing of adding it as a search engine to the Firefox Browser itself.

Still gets the four stars because it is a good extension, but I decided since I already use SSS a lot anyway that I'll just keep using that and leave this on the shelf. Thanks for the good times.

Problem with all words searched giving "Sorry, no definition found." resolved idiopathically. I am running Linux with a VPN, though.
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Handy for words that you kind of know, but kind of know there's more to the definition.

Would be neat if you could toggle what the More>> link does. Thinking along the lines of a thesaurus library that could be accessed without opening a new search for "define xyz".

Though, the primary utility of the app seems to be in obtaining definitions with minimal interruption and task switching, so maybe less is more.

a simple add-on that does the job but is there any way to change the pronounciation to U.S. speaker?

i like the simplicity of the graphics, the in-page pop-up, the short defintions and the google-generated content is better than competitors (mirriam webster, for example), HOWEVER, after a few hours of using, it started giving me "sorry, no definition found" for whatever i click on. this has not resolved even after uninstalling and reinstalling the add on, so very sad about this as it is otherwise exactly what i'm looking for.

if the developers see this i can't tell you what triggered the add in to stop working. i made sure dom.webcomponents.shadowdom.enabled was enabled (when it stopped working). I do read a lot of stuff on pocket and reader view so maybe it started after some interaction there? maybe there's a clue in the fact that functionality was not restored even after deleting and reinstalling?

EDIT (after response from developer): YES, you were right about it being a VPN issue. As soon as i switch it off the add-on starts to work again. I have changed my rating to 4/5. i tend to have my vpn on most of the time so using this add on will not be particularly useful to me after all, however, i am aware this will only affect a minority of users.

It's fast, simple, and practical for sure. It lacks privacy due to its Google use although you could try to use wordnik as a source as duckduckgo uses it.