Cognomen Синиак (Siniak 
, Синиак 
) , in all the world, is a rare family name. The cognomen Синиак is characteristic of Belarus, where it is a rare surname, Poland, where it is a very rare surname, and Argentina. Not in comparison with a country's population, it most frequently occurs in Russia, Poland, and Brazil. Also, Синиак is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Siniak | Brazil, Argentina, Poland, United States, Belarus |
| Синиак | Russia |