Cognomen איילין (Eileen 
, Aileen , איילין 
) , across the world, is quite a common surname. The cognomen איילין is habitual in Singapore, where it is quite a rare surname, Israel, and Malaysia. Not in comparison with a country's population, it is the most numerous in Indonesia, Mexico, and China. Much more frequently, איילין is the forename as well as the last name.