Last name 旬 (Tuan 
, 旬 
) , in all the world, is a common cognomen. The cognomen 旬 is habitual in Malaysia, where it is quite a common surname, Vietnam, and Macao. Measured by absolute frequency, it is commonest in South-eastern Asia, particularly Vietnam, Malaysia, and Philippines. More frequently, 旬 is the forename as well as the last name.