Delegate

A person authorized to act as representative for another; a deputy

A representative at a conference, etc.

An appointed representative in some legislative bodies

A type of variable storing a reference to a method with a particular signature, analogous to a function pointer

To authorize someone to be a delegate

To commit a task to someone, especially a subordinate

(of a subdomain) to give away authority over a subdomain; to allow someone else to create sub-subdomains of a subdomain of one's own