O. Ride
O/T
O/V
OAC
OAG
OAT
OATS
OB
OBOGS
OBRM
OBS
OC
OCA
OCC
OCCLUDED FRONT OR OCCLUSION
OCCULTATION
OCN
OCP
Octal
OCTAVE
OD
ODAP
ODAPS
ODID
ODL
ODS
OE
OEAS
OEI
OEM
OEU
Off-Block Time
OFP
ofs
OFSC
OFV
OGE
OGV
OH
ohm
OHU
OID
OIU
OLAN
OM
OMCF
OMD
Omega
Omega/VLF
Omnibearing
OMS
On-Block Time
ONC
OOOI
OP
ORBITAL ELEMENTS
ORBITAL PERIOD
ORBITAL VELOCITY
ORDER OF MAGNITUDE
ORIG
ORT
orthogonal
OS
OSC
OSI
OSI-RM
OSPF
OSS
OST
OT&E
OTA
OTF
OTFP
OTH
OTIS
OTS
OUTBD
OUTER FIX
OV
OVBD
OVERSEAS SAR REGION
OVERTEMP
OVG
OVHD
OVHT
OVLD
OVRD
OVS
OVSP
OW
OWE
OXIDIZER
Oxy
oz
OZONE