The name Eustacia is a girl's name of Greek origin meaning "fruitful". Eustacia and discussed in our forums with posts like "Picky Parents BNG".
From the experts:
Eustacia, the ancestor of mid-century fave Stacy, is just the kind of fusty old relic that might be polished up for modern use. Eustacia Vye is the central character of Thomas Hardy's The Return of the Native.