1. (n.) 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.

2. (n.) A woman who is closely allied to, or associated with, another person, as in the same faith, society, order, or community.

3. (n.) One of the same kind, or of the same condition; -- generally used adjectively; as, sister fruits.

4. (v. t.) To be sister to; to resemble closely.

Greek LPN RN abbess affiliate ally alter ego analogon analogue associate aunt auntie belonger blood brother brethren brother bub bubba bud buddy canoness card-carrier card-carrying member cardholder catechumen charge nurse charter member church member churchman churchwoman clergywoman close copy close match clubber clubman clubwoman cognate committeeman communicant companion complement comrade congenator congener conventioneer conventioner conventionist conventual coordinate correlate correlative correspondent counterpart country cousin cousin cousin once removed cousin twice removed daughter district nurse dues-paying member enlistee enrollee equivalent father fellow first cousin foster brother frater fraternity man graduate nurse grandnephew grandniece granduncle great-aunt great-uncle guildsman half brother honorary member image initiate insider joiner kid brother kindred spirit lady superior laic lay brother lay sister layman laywoman licensed practical nurse life member like likeness mate member mother mother superior near duplicate nephew niece novice nun nuncle nunks nunky nurse nursing sister obverse one of us parallel parishioner pendant picture pledge postulant practical nurse prioress private-duty nurse probationer probationist probe public health nurse reciprocal registered nurse religieuse school nurse scrub nurse second cousin second self secular secular canoness similitude simulacrum sis sissy sister-german sistern socius son sorority girl sorority woman soul mate stepbrother stepsister student nurse such suchlike superioress surgical nurse tally the like of the likes of the reverend mother trained nurse twin unc uncle uncs uterine brother visiting nurse