The Collaborative International Dictionary of English v.0.48:
Sororal \So*ro"ral\, a. [L. soror sister: cf. F. sororal.] Relating to a sister; sisterly. [R.] [1913 Webster]WordNet (r) 3.0 (2006):
sororal adj 1: like or characteristic of or befitting a sister; "sisterly kindness"; "sororal concern" [syn: sisterly, sisterlike, sororal] [ant: brotherlike, brotherly, fraternal]