Wikipedia
Khrui
The khrui is a light outer garment worn as a gown or robe in certain ceremonial settings in Thailand. It is long-sleeved and open at the front, and is made of a sheer or mesh fabric, lined with a band of satin, felt or other material, and may be exquisitely embroidered. Dating from at least the 17th century, it was originally worn only in the royal court, but nowadays is most recognisable as the form of academic dress employed by many universities, especially Chulalongkorn University.