late 14c., susterhede, "state of being or having a sister; sisterly relationship," also figurative; from sister + -hood. The meaning "a society of sisters" (usually a religious order) is from mid-15c.; the sense of "women having some common characteristic or calling" is by c. 1600. Sisternity, on the model of fraternity, also was used in 17c. for the "institution or convent society" sense; sistership was tried form this from 1840.
updated on November 21, 2022