Last name Radai (รัศมี 
, Radai 
, Радай 
) , in all the world, is quite a common cognomen. The cognomen Radai is characteristic of Thailand, where it is quite a rare surname, Hungary, and Romania, where it is a rare surname. Not in comparison with a country's population, it is the most numerous in Thailand, Hungary, and Mexico. More prevalently, Radai is the forename as well as the last name.