The city draws its name from the spiny broom (calicotome spinosa; brnistra or žuka in modern Croatian), a common shrub in the area, after which the Greek colony of Aspálathos (Aσπάλαθος) or Spálathos (Σπάλαθος) was named.
For a significant period, the origin of the name was erroneously thought to be related to the Latin word for "palace" (palatium), a reference to Diocletian's Palace which still forms the core of the city.