Sioux \sioux\ as a girl's name is a variant of Susan (Hebrew), and the meaning of Sioux is "lily".

The baby name Sioux sounds like Sue, Cilla, Sha-, Shaya, She-, Shea, Shaye, Shay, Shae, Shilla, Tia, Xia, Zia, Zilla, Zoe, Zoya, Zooey, Zoie, Zoey, Zoee and Zoia. Other similar baby names are Dix, Nix and Siouxsie.