Cognomen ส้าย (Sai 
, ส้าย) , all around the world, is a widespread last name. The family name ส้าย is habitual in Mongolia, where it is a prevalent surname, Myanmar, where it is a common surname, and Malaysia, where it is quite a common surname (explore the name in all countries). In absolute terms, it is commonest in Myanmar, India, and Mongolia. More frequently, ส้าย is the forename as well as the last name.