blacklist

noun

1. A list or set of people or entities to be shunned or banned, disallowed or blocked.

   “The software included a lengthy blacklist of disreputable websites to block.”

verb

1. (transitive)To place on a blacklist; to mark a person or entity as one to be shunned or banned.

   “You can blacklist known spammers with that button.”

   “As the world's drug habit shows, governments are failing in their quest to monitor every London window-box and Andean hillside for banned plants. But even that Sisyphean task looks easy next to the fight against synthetic drugs. No sooner has a drug been blacklisted than chemists adjust their recipe and start churning out a subtly different one.”