fully qualified domain name (FQDN)
A fully-qualified domain name (FQDN) is that portion of an Internet Uniform Resource Locator (URL) that fully identifies the server program that an Internet request is addressed to. The FQDN includes the second-level domain name (such as "whatis.com") and any other levels (for example, "www.whatis.com" or "www1.somesite.com"). The prefix "http://" added to the fully-qualified domain name completes the URL.