In its current form, it is a tight-fitting silk tunic worn over pantalons.
The word is pronounced “ow zai” in the North and “ow yai” in the South of the country.
“Áo” is derived from a Middles Chinese word meaning “padded coat”.
“Dài” means “long”
The word “áo dài” was originally applied to the outfit worn at the court of the Nguyễn Lords at Huế in the 18th century.
This outfit evolved into the “áo ngũ thân”, a five-paneled aristocratic gown worn in the 19th and early 20th centuries.
Inspired by Paris fashions, Nguyễn Cát Tường and other artists associated with Hanoi University redesigned the “ngũ thân” as a modern dress in the 1920s and 1930s.
The updated look was promoted by the artists and magazines of Tự Lực văn đoàn (Self-Reliant Literary Group) as a national costume for the modern era.
In the 1950s, Saigon designers tightened the fit to produce the version worn by Vietnamese women today.
The dress was extremely popular in South Vietnam in the 1960s and early 1970s.
On Tết (Vietnamese New Year) and other occasions, Vietnamese men may wear an “áo gấm” (brocade robe), a version of the ao dai made of thicker fabric.
Academic commentary on the ao dai emphasizes the way the dress ties feminine beauty to Vietnamese nationalism, especially in the form of “Miss Áo dàii” pageants, popular both among overseas Vietnamese and in Vietnam itself.
“Áo dài” is one of the few Vietnamese words that appear in English-language dictionaries.