1. (noun)Ob, Ob River a major river of western Siberia; flows generally northward and westward to the Gulf of Ob and the Kara Sea Synonyms: obstetrics, tocology, midwifery
2. (noun)obstetrics, OB, tocology, midwifery the branch of medicine dealing with childbirth and care of the mother Synonyms: obstetrics, tocology, midwifery