If a website is blacklisted, it has been excluded and disallowed from the list. For instance, we use the term “blacklisted” to refer to sites excluded from a list of safe sites with our website checking tool. Sucuri is a well-known website security site that uses the term “blacklisted” to describe a site labeled as malicious by a security vendor. Once a site has been labeled as malicious by a security vendor, it needs to fix its suspicious activity before it gets off the blacklist.
Related terms: Blocklist.
Blacklist and blocklist are interchangeable. We use blocklist whenever possible; however, we will use blacklist if blocklist is already used or to stay true to the terminology used by a specific tool.