Since Opera 15+ is now based on the Chromium project, I decided to port the plugin from Chrome. So you can now access the JLect dictionary using either the context menu feature or the toolbar button.
It's a very simple extension, but hopefully some of you may find it useful:
JLect Search
https://addons.opera.com/en/extensions/details/search-jlect/?display=en
Cheers (o^_^o)