Sentence:  Besides , Miss Henrietta - as she was generally known since she had put up her hair with a chignon in the back - had little time to spare them from her teaching and writing ; so Cyrus Adler became interested in her friend Racie Friedenwald , and Joe Jastrow - the only young man who when he wrote had the temerity to address her as Henrietta , and signed himself Joe - fell in love with pretty <WSD>sister</WSD> Rachel . 
Meaning of the word marked with <WSD> tags:  a female person who has the same parents as another person