Definition of "OB"

OB

noun
countable and uncountable, plural OBs
1. (sports) Initialism of Olympic best.
2. (television, radio) Initialism of outside broadcast.
3. Initialism of old boy. (male graduate; also a CB radio operator's term of address for a male)
4. Abbreviation of obstetrician.
  Quotations
  One woman in ten is at risk — yet one-third of all women over 50 have never had a mammo! By making Pap tests routine, OBs and GYNs have saved many lives.
  1989, Contemporary Obstetrics-gynecology, volume 33, page 200
5. Abbreviation of obstetrics.
6. Abbreviation of Old Babylonian.
adjective
not comparable
1. Abbreviation of obstetric.
2. (golf) Initialism of out of bounds.
3. Abbreviation of obligatory. (as in "ob. link" on Usenet) (see ObLink at c2.com; see also ob-)
4. Abbreviation of Old Babylonian.