Cognomen Kośny (Kośny 
) , all over the world, is a very rare last name. The last name Kośny is habitual in Eastern Europe, particularly Poland, where it is a rare surname.
| VARIANT | COUNTRY |
|---|---|
| Kośny | Poland |
| maksymilian kośny PL (b. 1905) |
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| witold kośny DE (b. 1937) |
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| marek kośny Polish researcher, PL |
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