Народная этимология
Folk etymology attributes the city name to a fisherman, Wars, and his wife, Sawa. According to legend, Sawa was a mermaid living in the Vistula with whom Wars fell in love. In actuality, Warsz was a 12th/13th-century nobleman who owned a village located at the modern-day site of the Mariensztat neighbourhood. The official city name in full is ("The Capital City of Warsaw").