sororEtymologyPIE word *swésōr Shortening; also from Latin soror (“sister”), akin to frater from Latin frāter (“brother”). Doublet of sister.nounA sorority sister; a fellow member of one's sorority.“Gathering your fraters and sorors / If you were a member of a fraternity or sorority in college, gather your old fraters (brothers) and sorors (sisters) for a reunion.”