Synonyms for OB (same or very similar meaning)
WordNet sense 1 (a major river of western Siberia; flows generally northward and westward to the Gulf of Ob and the Kara Sea):
Ob RiverWordNet sense 2 (the branch of medicine dealing with childbirth and care of the mother):
midwifery, obstetrics, tocologyFrom the ODE community, based on WordNetadd/edit