Cognomen Mocnaj (Mocnaj 
) , across the world, is a very rare last name. The cognomen Mocnaj is habitual in Croatia, where it is a rare surname, Australia, where it is a very rare surname, and Canada. Measured by absolute frequency, it is commonest in Croatia, Australia, and the United States.
| VARIANT | COUNTRY |
|---|---|
| Mocnaj | Croatia, Canada, United States, Australia |