Surname Auin (Auin 
) , around the world, is a very rare last name. The cognomen Auin is habitual in Thailand, where it is a very rare surname, Argentina, where it is an extremely rare surname, and the United States. Not in comparison with a country's population, the name is most common in Thailand, India, and Argentina. Very seldom, Auin is the forename as well as the last name.