subdomain

plural subdomains

1. A domain or sphere that is part of a larger domain or sphere.

   As a technical subdomain of biology ecological investigations have evolved from what has been traditionally called natural history.

   1971, Jacob Robert Kantor, The logic of modern science

2. InternetA domain name that has been prefaced with additional parts separated with periods.

   "We hope that the parties responsible for managing the security of this subdomain will take this as a wake-up call, and not as a threat," a note on the page said.

   2012 July 13, Doug Gross, “Yahoo hacked, 450,000 passwords posted online”, in CNN Business, archived from the original on 17 Aug 2022

   3 more examples

   A domain is a subdomain of another domain if it is contained within that domain. This relationship can be tested by seeing if the subdomain's name ends with the containing domain's name. For example, A.B.C.D is a subdomain of B.C.D, C.D, D, and " ".

   1987 November, P. Mockapetris, Domain Concepts and Facilities, RFC1034, also known as STD0013

   BIND 9 Administrator Reference Manual (9.3.2), Copyright © 2004, 2005 Internet Systems Consortium, Inc. ("ISC"), Copyright © 2000-2003 Internet Software Consortium, https://web.archive.org/web/20060619063455/http://www.bind9.net/manual/bind/9.3.2/Bv9ARM.ch01.html Every name in the DNS tree is a domain, even if it is terminal, that is, has no subdomains. Every subdomain is a domain and every domain except the root is also a subdomain.

   On July 8, 2025 Glitch project hosting and user profiles will be shut down. Your Glitch dashboard will remain available as usual through the end of 2025, with access to download all of your code for your projects, as well as a new feature to set up redirects for your project subdomains so your URLs keep working.

   2025 May 22, Anil Dash, “Important Changes are Coming to Glitch”, in Glitch, archived from the original on 15 Aug 2025

3. InternetAn additional part prefaced to a domain name.

   In en.wiktionary.org, en is a subdomain.