Surname ثانوي (ثانوي 
) , worldwide, is a rare cognomen. The family name ثانوي is characteristic of Iran, where it is a rare surname, Egypt, and Saudi Arabia, where it is a very rare surname. Measured by absolute frequency, it is the most numerous in Iran, Egypt, and Algeria.
| VARIANT | COUNTRY |
|---|---|
| ثانوي | Saudi Arabia, Iran, Yemen, Algeria, Egypt |