Collection

Acronyms

Abbreviations, definitions, references, and remarks.

Words shorter than three characters are ignored. Every remaining word must match somewhere in the record.
Showing 4,301–4,350
AcronymDefinitionReferenceRemarks
OGolive green (uniform color)Army
OGWW II Convoy designationUK to Gibraltar
OhioOhio Movement
Pre-World War II, slogan of one-year men to go "over the hil…
Pre-World War II, slogan of one-year men to go "over the hill" in October when their Army commitment was up.
OIOperation Instruction
OICOfficer in Charge
OIGOffice of Inspector General
OLFOutlying GieldNavy
OLIVEWW II code nameWW II Attack on Gothic Line, Italy
OLYMPICWW II code nameWW II Plan for March 1946 invasion of Kyushu, Japan
OMAHAWW II code name
Normandy beach assaulted by troops of U.S. V Corps, June 6 1…
Normandy beach assaulted by troops of U.S. V Corps, June 6 1944
OMCOffice of Munitions ControlState Dept
OMSOrganizational Maintenance SquadronAF
ONWW II Convoy designationUK to North Africa (fast)
ONIOffice of Naval Intelligence
ONSWW II Convoy designationUK to North America (slow)
OOBOrder of Battle
OPObservation Post (or Outpost)Korean War
OPAOffice of Program AppraisalNavy
OpAreaOperating Area
OPCENOperations Center
OPCOMOperational Command
OPCONOperational control
OPDECOperational Deception
OPDEC PLOperational Deception Planner
OPDEC PLNOperational Deception Planning
OPDSOffshore POL Discharge System
OPECOrganization of Petroleum Exporting Countries
OPEVALOperational EvaluationNavy
OPLOutpost lineArmy
OPLANOperations plan
OPLOOutpost LIne of Observation
OPLROutpost Line of ResistenceKorean War
OPLROutpost LIne of Resistence
OPLROutpost line of resistenceArmy
OpnOperation
OpNavOffice of Naval Operations
OpnOOperation OrderMC
OpnPlanOperaton PlanMC
OpnsOperations
OPORDoperation order
OpPlanOperation plan
OpsOperations
OPSECoperations security
OPTECU.S. Army Operational Test and Evaluation CommandArmy
OQMGOffice of Quartermaster GeneralArmy
OROfficial Records of the War of the RebellionCivil Wa records
OROperational Readiness
OROperational RequirementNavy
OROperations Research
OR/SAOperations Research/Systems Analysis
Background and Sources Collection notes, historical context, and related resources

Abbreviations and Codes

All large organizations have their own terminology, or seemingly sometimes their own language. The American military establishment is certainly no exception. In fact, being so large and diverse, it has probably more unique terminology than almost any other. First are the many abbreviations and initials for names of organizations, then there are the acronyms for just about everything, and also the many code words for operations.

Some of the acronyms and code words are included in the database table that is behind this page. A great many more are included in the sources that are linked below.

For initials, first there is GI, from World War II, originally meaning Government Issue, then as a noun meaning the soldiers, the GIs. Another example of abbreviations is the Navy and Marine Corps method of identifying the types of their aircraft squadrons. For example, VT first meant Torpedo Squadron (including VT8, the Navy’s Torpedo Squadron 8, which had all of its planes lost on a single raid during the Battle of Midway). Modern VT squadrons are training squadrons. In World War II, training squadrons were identified as VN.

Then there is the current FYDP (fiedep), or the Five Year Defense Plan. More complicated are the acronyms, or a kind of shorthand, particularly in the Navy, such as DesRon for Destroyer Squadron and CinCPacFleet, for Commander in Chief, Pacific Fleet. A comprehensive dictionary of terms currently used by the U.S. military establishment is Joint Publication 1-02 (DoD Dictionary of Military and Associated Terms), prepared by the Joint Chiefs of Staff: JCS Pub. 1-02.

Another segment of the unique terminology is the code words for operations, probably the most famous of which is Operation Overlord, which was the code name for the invasion of Normandy in 1944. A very good source for information about the code words for operations in World War II is the U.S. Army’s own list: Army Code List.