OA
Osteoarthritis
OB
Obstetrics
OBS
Organic brain syndrome
od
Once daily
OOB
Out of bed
O.P.
Outpatients
O.R.
Operating room
ORIF
Open reduction, internal fixation
OT
Occupational therapist/therapy
OTR
Occupational therapist (official signature)
oz.
Ounce
O:
Objective