Seldom used in American culture, xu is a word of both Vietnamese and French descent. Xu was a monetary subunit of the dong, which is the currency used in Vietnam. It’s equivalent to the cent and was formerly minted in South Vietnam. As an aluminum coin, it didn’t hold much value. In fact, it was the 100th part of a dong. The xu meaning dates back to 1948, which means the xu didn’t live a long life. Much like the xu definition, the origin of the phrase is fascinating. Surprisingly, it comes from the French word sou. Sou translates to penny, which is essentially what xu was.