Cognomen Joonus (Joonus 
) , worldwide, is a rare surname. The cognomen Joonus is habitual in Sri Lanka, where it is a rare surname, China, where it is an extremely rare surname, and the United States. Measured by absolute frequency, the name is most common in Sri Lanka, China, and India. Very seldom, Joonus is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Joonus | United States, Sri Lanka, India, China |