The domain dictionaryext.xyz is blocked because it is a search hijacker that delivers a forced Firefox extension. This potentially unwanted program (PUP) is forced on users because they are unable to leave the site until they have installed the extension.
The website claims you need to update Firefox.
Should users wish to visit a blocked Domain and exclude it from being blocked, they can add it to the exclusions list. Here’s how to do it.
Select your language