Cognomen 洪寅 (洪寅 
) , in all the world, is a rare surname. The last name 洪寅 is habitual in Eastern Asia, particularly China, where it is an extremely rare surname. More prevalently, 洪寅 is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| 洪寅 | China |