Cognomen 洞 (Uro 
, 洞 
) , all around the world, is a common surname. The last name 洞 is habitual in Finland, where it is quite a rare surname, Argentina, where it is a rare surname, and India. Measured by absolute frequency, it is the most numerous in India, China, and Nigeria. Likewise, 洞 is the forename as well as the last name.