What is "female sibling"

Usage examples of "female sibling".

Any man could take any woman whenever he wished to relieve himself, with the exception, through long tradition, of his female sibling.

The elder female sibling I do not know as well but she is eager and insistent.

Eierkopf's earlier hypothesis that no female sibling, even a twin, could be the GILES, either also or instead.

This time I closed my eyes before the flash did, and I opened them to make the propitiating gesture and see the only female sibling, _Nu Pa_, who seemed to be a low cloud no more than two feet tall.