I can't find the word in my dictionary, and Google Translate translates it as 'ancestor' but I'm not sure how accurate that is.
I'm trying to translate this sentence:
この葛葉家の屋敷で働く使用人はほぼ全員が一族の神祖であった『お狐様』を讃えるために狐の面をつけている。
However I'm not exactly sure what 神祖 means.