Surname Косин (Kosin 
, Cosin 
, Косин 
) , across the world, is quite a rare family name. The cognomen Косин is characteristic of Slovenia, where it is quite a rare surname, Bulgaria, and Slovakia. Measured by absolute frequency, this name is the most popular in Germany, the United States, and Spain. Likewise, Косин is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Kosin | Germany, Nigeria, United States, Thailand, Poland |
| Cosin | Germany, Spain, Nigeria, United States, Brazil |
| Косин | Uzbekistan, Russia, Belarus, Bulgaria, Ukraine |
| Kosyn | Poland, South Africa, United Kingdom, Thailand |
Koshin, Kosine, and Masatsukasa