Probably the best dictionary that I've tried here, so far.

works great. thanks to developer(s).

Many thanks to Mr Thắng. I don't understand why's so few users and ratings for this amazing app. I have one opinion: You can add suggestion in column side-by-side view. It's will make this addon get 10/10 point.
Rất khuyên mọi người tải add-on này. Từ điển này rất chi tiết.

Tốt nhưng cần cải thiện thêm.
Ví dụ khi double click chọn từ boats - bên nghĩa tiếng Việt -VI là "thuyền" rất ngắn gọn, nhưng bên nghĩa tiếng Anh -EN rất chi tiết phát âm, loại từ là danh từ và động từ ( cài đặt ngôn ngữ chính là VI, sau đó là EN ).
Cảm ơn rất nhiều.

good job man, right what i need. Wait for double click translate and more dic

Hi,

Blessed be the creator of this sweet piece of jewellery. Works absolutely great on double-click.

Discreet and fast. Also suggests other languages in which the word exists in case it misunderstood the request.

Dictionaries are extensive and comprehensive.

Bravo.

Add-on rất tuyệt vời, hữu ích. Dịch nghĩa, ví dụ đầy đủ, thậm chí còn có cả ghi âm của từ nữa.
Nhưng mà nhiều từ mình tra từ Tiếng Anh -> Tiếng Việt thì phần phiên âm hiện không đầy đủ, có khi chỉ hiện một vài âm nhưng may mà chuyển qua Anh -> Anh lại được. Không biết là do tiện ích hay do Wiki nữa.
Với lại khi sao chép văn bản mà không phải là trang web trực tuyến, ví dụ như văn bản trong máy tính mở bằng firefox thì tiện ích không hoạt động.
Dù sao thì tiện ích cũng rất hay mà còn đơn giản nữa.

Was able to install and create 2 languages (english, german).

Issues: Popup text does not seem to work. Is there a setting to activate it? I would prefer the hover search rather than side panel.
Is there any option to add another language? or a relationship like "German - Spanish", so that the translation appears first?

So useful to translate! I love the IPA. But there's always the side panel, I'd like to use the popup window, but I don't know how. And I would like to add more language, than the 2 preconfigured language you can add to switch from one to the other one.

The only missing feature is to save words or expressions.

phải login thank bác cái :))

Very useful, thank you!
It'd be nice to have a default behavior which displays the result according after say "250ms" without having to clickclickclickclick

add-on rất hữu ít.
nếu có hổ trợ tra từ trong phần View PDF nữa thì hay quá.

A really great extension. Thank you for your work. I have been using Zen’s, great too, but old and no more updated “Wiktionary and Google Translate” add-on for many years. Your extension seems to be the only one that meets similar dictionary-translation demands, even more successfully in most aspects, may be less in some others (in which cases Mozilla’s changed demands seems to be the major restrictive factor).

Unfortunately, my Quick Dictionary installation (2.03a0 on FF 52.9.0) is not working properly:

The Toolbar Button is not working at all.
The Sidebar option and the Context Menu option are missing.
There is no Shortcut Activation option (by pressing Ctrl + Q (?) or Ctrl + Shft + Q (?) Quick Dictionary is not activated).

The Configuration Options and the Quick Button-Popup options are functioning properly, except that there is no option to move the popup window (like in this video: https://gfycat.com/YellowishWastefulDove)

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Edit 19/3/19

Hi Trần Xuân Thắng,
Thank you for your answer and for Quick Dictionary which is my favorite extension that I use all-day.
I’m now using it on FF 65 and off course the previously mentioned problems are all gone.
One thing I’m missing, which would be great if QD had got, is the direct (without pre-selection), single word lookup. This feature is ideal for the translation even of youtube subtitles words (which are not selectable).
Except from Zen’s addon (Hover + Ctrl/Alt), I have also seen it employed in “Dict.cc Translation” extension (Ctrl/Shift/Alt + Click).

It's so quick and easy to get a spelling or a definition. That's all I wanted and it was the only way I could find to meet those needs. I don't know if there are other ways to get there but it was what I found.