extensions.customizegoogle.misc.filtercolor

Using the preference “extensions.customizegoogle.misc.filtercolor” in about:config you can control
the color of a filtered URL. If it’s not there, you’ll have to create it. The default color is grey (”#aaaaaa”).
This way you can make it disappear (”#ffffff”) or stand out (”#ff8000″).

Ideal for making wikipedia, itself a neologism, vanish from results