(also CNAME, true name)
Canonical name definition
A canonical name is a type of database record in the domain name system that indicates that a domain name has an alias or a nickname.
Canonical name examples
If you have a domain name thisisanexample.com and www.thisisanexample.com pointing to the same application, a canonical name is a way to avoid maintaining two records. In this case, the record of www.thisisanexample.com will point to a server IP address, while the canonical name thisisanexample.com will point to www.thisisanexample.com.