adj. Related through someone's sister, e.g. sororal nephew.
the GNU version of the Collaborative International Dictionary of English
adj. Relating to a sister; sisterly.
The Century Dictionary and Cyclopedia
Of or pertaining to a sister or sisters; sisterly.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. like or characteristic of or befitting a sister
Word Usage
"However, after Leah’s marriage to Jacob, Leah’s sister Rachel also became a primary wife to Jacob — a marriage arrangement known as sororal polygyny."