.onion is a special-use top-level domain name designating an anonymous onion service, which was formerly known as a "hidden service", reachable via the Tor network. Such addresses are not actual DNS names, and the .onion TLD is not in the Internet DNS root, but with the appropriate proxy software installed, Internet programs such as web browsers can access sites with .onion addresses by sending the request through the Tor network.
via Wikipedia infobox
.onion is a special-use top-level domain name designating an anonymous onion service, which was formerly known as a "hidden service", reachable via the Tor network. Such addresses are not actual DNS names, and the .onion TLD is not in the Internet DNS root, but with the appropriate proxy software installed, Internet programs such as web browsers can access sites with .onion addresses by sending the request through the Tor network.
The "onion" name refers to onion routing, the technique used by Tor to achieve a degree of anonymity.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).