Needs some options, often present in add-ons:
- selection – other than by double click
- hot-key activation / open with a bubble . . .
- contextual menu
- history
- define the position and the dimensions of the pop-up

Sometimes, reinstalling solves some problems.

I love this. It's fast and informative.

Definitions are often incomplete or just wrong. Removed it after checking "limns" and getting "plural form of limb." At least I got a laugh out of that one.

It's good except for the fact that the dictionary used is not giving a really clear definition of the words to be checked.
I suggest using the Oxford Dictionary for your app.

Good

Works well, but I don't like the fact that a large popup blocks the page whenever I double click a word.

Better alternatives for me would be getting the popup from the right-click context menu, or maybe by clicking on a small bubble that appears after double clicking (like with some of the translator add-ons).

It does what I need.

It does what it says, which is great, and even more great is the fact that I don't have to manually install any dictionaries or do much configuration. The only sore point for me is the need to double click a word to highlight it, which is less practical (IMHO) than a selecting a word with the mouse and getting to see its meaning via the context menu. Some websites, including news outlets, set up scripts to show popups on double click, which is why a context menu option is more desirable in such cases. I hope the developers introduce this option in later versions.

better than the chrome extension!

Thank you, this was the only thing I missed after switching back from Chrome to Firefox.

Doesn't show all of the meanings.

Would be 5 stars, but it is unusable on dark/black backgrounds, which is mainly what I use it on.

Does what it says!

This is fairly close to the original Google Dictionary extension on Google Chrome. Is it possible to add options for trigger / hotkeys? i.e. Being able to use Ctrl / Alt / Shift with a click?

Great tool. Have to knock a star off for its inability to be read over dark backgrounds.