Cognomen Oriordan (Oriordan 
) , globally, is quite a rare surname. The surname Oriordan is habitual in Ireland, where it is quite a common surname, the United Kingdom, where it is a rare surname, and Australia. In absolute terms, the name is most common in the United States, Ireland, and the United Kingdom. Much less frequently, Oriordan is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Oriordan | United Kingdom, Australia, Indonesia, United States, Ireland |