Deindexing is the removal of a URL from search engine results while the underlying webpage still exists on its host. The page may remain reachable by direct link, but it becomes much harder to discover through normal search.
In cyber security, deindexing matters because visibility controls risk. Defenders may request deindexing for leaked credentials, personal data, or phishing pages to reduce exposure and limit harm. Search providers can also use it to suppress known malicious or abusive content. Attackers, however, may try to deindex lure pages from public view or hide supporting infrastructure from casual discovery. Deindexing is not deletion, so security teams still need takedowns, access controls, and monitoring of the original host.