I am really frustrated that Firefox does not provide the three-finger-tap lookup operation is in built in OS X. What is baffling me is that it supports other gestures such as two finger swipes and taps. So why not the 3 finger tap dictionary ?

Is this possible to actually implement ? Or is it because access to in built dictionary and trackpad is blocked by OS ? How can I start looking at this problem ?

  • On force touch will directly open lookup.
    – DawnSong
    Feb 22, 2020 at 1:46

4 Answers 4


As of now (Dec 1 2014), although the option is not present in right-click menu, three-finger dictionary lookup works perfectly fine in my Firefox (Developer Edition 35)

Also there have been certain plugins which help you look up words in dictionary through right click. For example https://addons.mozilla.org/en-US/firefox/addon/look-up-in-dictionary-7261/

EDIT (Oct 2017): I'm now using the new e10s Firefox and the dictionary lookup still works. You don't need any plugin, just tap with three fingers or press Control + Cmd + D.

  • 1
    Triple-finger lookup works for me (Firefox 39), but there's a subtle bug. I first need to click somewhere on the page. Without this first single click, triple-finger gesture is ignored on newly opened pages. Details: bugzilla.mozilla.org/show_bug.cgi?id=687026#c26
    – ash
    Jul 25, 2015 at 12:23
  • 3
    CTRL+CMD+D works for me. tested on firefox 70.0 on OSX 10.15 Nov 8, 2019 at 19:16
  • @ash One force touch works OK. I set my trackpad to "Force click with one finger to Look up & data detectors"
    – DawnSong
    Feb 22, 2020 at 1:47

Unfortunately looks like this is still an open bug as of today.


  • 1
    yes I am aware of that. but i was thinking of fixing it and hence want a point to start...
    – user775093
    May 6, 2014 at 4:03

Firefox bug #687026 regarding 10.7 - 10.10 was fixed Jan 2016.

Firefox bug #1212527 regarding 10.11 was fixed in May 2016. Firefox 49+ has the fix.

Working as expected on 10.11 and 10.12.

  • Confirming. Once enabled in System Preferences, it works as expected in Firefox under macOS Sierra/Firefox 49+.
    – dr.nixon
    Oct 6, 2016 at 16:17
  • @dr.nixon How did you do that? Could you explain with more details, please?
    – DawnSong
    Jun 6, 2018 at 11:29
  • System preferences -> trackpad -> point and click -> look up & data detectors.
    – dr.nixon
    Jun 7, 2018 at 19:35

One can open the MacOS dictionary by typing dict://word-in-question in the address bar.

This extension: https://addons.mozilla.org/en-US/firefox/addon/macos-dictionary-lookup/ adds a menu item to do it. In order for it to work, you need to do the above process manually, and allow Firefox to open the dictionary app.

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