The name Sia is a girl's name meaning "Victory". Sia and is often added to lists like Names That Mean Victory and discussed in our forums with posts like "Hunt for our favourite girl names (Alphabet-wise)".
From the experts:
Mia, Gia, and now Sia!
Born Sia Kate Isobelle Furler, the Australian singer-songwriter scored a major international hit with "Chandelier" in 2014, and put her short, uncommon name on the radar.
Sia can be a variation of the many Old Norse names derived from the element sigr, victory. But it could also be short for names like Sophia, Sienna, and Cecilia.