In what year did Sigismund Casimir's mother die?
Cecilia Renata of Austria Archduchess Cecilia Renata of Austria (German: "Cäcilia Renata"; Polish: "Cecylia Renata"; 16 July 1611 – 24 March 1644) was Queen of Poland as consort to the Polish-Lithuanian Commonwealth's King Władysław IV Vasa.
Sigismund Sigismund (variants: Sigmund, ) is a German proper name, meaning "protection through victory", from Old High German "sigu" "victory" + "munt" "hand, protection". Tacitus Latinises it "Segimundus". There appears to be an older form of the High German word "Sieg" (victory): "sigis", obviously Gothic and an inferred Germanic form, and there is a younger form: "sigi", which is Old Saxon or Old High German "sigu" (both from about 9th century). A 5th century Prince of Burgundy was known both as "Sigismund" and "Sigimund" (see Ernst Förstemann, "Altdeutsche Personennamen", 1906; Henning Kaufmann, "Altdeutsche Personennamen", Ergänzungsband,1968).