1. A female who has the same parents with another person, or who has one of them only. In the latter case, she is more definitely called a half sister. The correlative of brother. I am the sister of one Claudio. (Shak)
Origin: OE. Sister, fr. Icel. Systir; also suster, from AS. Sweostor, sweoster, swuster, akin to OFries. Sweester, suster, LG. Suster, suster, D. Zuster, OS. & OHG. Swestar, G. Schwester, Icel. Systir, Sw. Syster, Dan. Soster, Goth. Swistar, Lith. Ses, Russ. Sestra, Pol. Siostra, L. Soror, Skr. Svasr. Cf. Cousin.