Eustace
The origin and history of Eustace.
Etymology
Came from the Old French form of Latin Eustathius, from Ancient Greek Εὐστάθιος (Eustáthios, “ancient name, also of a Christian saint”), from Ancient Greek εὐσταθής (eustathḗs, “steadfast, stable”). Alternatively it may come from εὔστᾰχῠς (eústăkhŭs, “fruitful”, literally “abundant in grain”), from εὖ (eû) and στάχυς (stákhus). It's a doublet of Ostap.
