Sigismund (variants: Sigmund, Siegmund) is a German proper name, meaning "protection through victory", from Old High German sigu "victory" + munt "hand, protection".
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).
A Lithuanian name Žygimantas, meaning "wealth of (military) campaign", from Lithuanian žygis "campaign, march" + manta "goods, wealth",[1][unreliable source?]
The Polish spelling is Zygmunt, and the Serbo-Croatian variant is Žigmund.