FQDN
From Wistful.net
FQDN == Fully Qualified Domain Name.
The FQDN is composed of the hostname and the domain name. Together they form the fully qualified domain name. The hostname is merely the single element used to identify a host (server or workstation) within a DNS zone. All names within a DNS zone must be unique.
Say you have a server name jose within the sub.domain.tld zone. jose.sub.domain.tld would be the FQDN of the host jose.

