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Is there way to do the right click "Look up in Dictionary" option on Firefox?

Also, I tried the right click "Search in Google" option in Mac Mail, however it wouldn't open up my default browser, Firefox. I uninstalled Safari. I'm guessing it only works on Safari and that's why it's not opening up Firefox.

you uninstalled safari?...... did you set the default browser in safari's preference?

You can install some extensions for firefox which is capable of looking up the word in several online dictionaries.
such as this one https://addons.mozilla.org/en-US/firefox/addon/1171
howitworks.gif
 
Another cool addon to do this

https://addons.mozilla.org/en-US/firefox/addon/12017

Highlight the word to look up and select "Look Up in Dictionary" from the right-click menu.
Alternatively, you can press shortcut key (Command-;) after highlighting the word.
When you are using right-click menu rather than shortcut key, you don't really need to highlight the word, because DictionaryFox tries to fetch the word under mouse cursor automatically.
Shortcut key combination is configurable. Select "Tools > DictionaryFox" from the menu bar.
Optionally, you can record history of the words you look up in Twitter. Select "Tools > DictionaryFox" from the menu bar and set Twitter account information.
Works on Mac OS X 10.4 and above on Intel Mac.
 
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