Rated 1 out of 5 stars
Sadly, Wikilook is broken again. Maybe someone can make it work again but, considering that the last update was over four years ago, I don't hold much hope.
I can confirm what kolika33 mentioned: Wikilook 2.7.0 conflicts with Adblock Plus. When Wikilook is active, Adblock Plus can't save custom filters. Strange, but true.
Meanwhile, I have found a good alternative for Wikilook. It's not 100% the same, but close enough, and in some respects even better. It's "Wiktionary and Google Translate" (https://addons.mozilla.org/en-US/firefox/addon/google-dictionary-and-google-t/). Try it if you're looking for a Wikilook replacement.