An ancient string instrument (chordophone), originating in ancient China; its nature is not known but was probably a zither-like rectangular body featuring silk or gut strings played with a bow.
"Archaeologists believe the rare artifact discovered in the tomb was an ancient zhu, likely played by sliding a bow across gut strings stretched over a rectangular frame."
A Chinese surname, from Chinese.
"My neighbor's last name is Zhu, and he invited our whole family over for dinner yesterday."