SISTER  , the correlative of

brother (q.v.), a female in her relation to the other children born of the same parents, also one who has acquired such relationship by marriage, a sister-in-law, or by adoption . The O . Eng. word was sweostor; cf . Dutch zuster, Ger . Schwester, Goth. swistar; in M . Eng. this appears as suster; the Scandinavian form appears in Icel. systir, Swed. systor, Dan. systor, and this has curiously taken the place of the true English form suster . Outside Teut. are found Lat. soror for sosor, Skt. svasti; the origin is not known, but it may be related with Skt. svasti, happiness, joy . The Lat. consobrinus, which has given " cousin," is from con-sobrinus, sosbrinus, from the stem of soror, sister . As " brother " and " brethren " are used for the male members of a religious body or community, so also is " sister " for the female members; more particularly it is applied to the members of a female religious order or community, a " sisterhood," in the Roman and other churches, who are de-voted to a religious life, works of charity or mercy, whether bound by irrevocable vows or not .