Lion introduced a new feature called look up:
… which can be invoked by double-tapping a word with three fingers. This works fine most of the time, but I've noticed that it fails many times in Google Chrome (I'm running 18.0 beta).
For example, it works fine on this website, but fails on http://www.gigaom.com. If I try both websites on Safari, they both work. Why does Chrome have this problem? Is it an issue with the website owner not following standards? Is it a bug in Chrome? Is there any temporary workaround?
Best Answer
This bug is known to the Chrome developers and has been filed under...
Issue 90461: Dictionary keyboard shortcut doesn't work in Lion
Basically the problems are timing issues for some websites which take too long to respond to information needed to show the dictionary.
This is what @resek@chromium.org says: