Definitions for unlistedʌnˈlɪs tɪd
Random House Webster's College Dictionary
not listed; not entered in a list or directory:
an unlisted phone number.
(of a security) not admitted to trading privileges on an exchange.
Origin of unlisted:
not on a list
"an unlisted telephone number"
not having your name entered on a voting list
"an unlisted voter"
Not included in a list; especially, a phone number not published.