Military records, whether of a soldier of a unit, are often packed with mysterious abbreviations. This page should help you understand what it all means.

Abbreviations

AA : Anti-Aircraft
AA : Army Act
AA & QMG : Assistant Adjutant and Quartermaster General
AASC : Anti-Aircraft Searchlight Company
AASS : Anti-Aircraft Searchlight Section
AB : Army Book
ABPO : Advanced Base Post Office
ACG : Assistant Chaplain General
ACI : Army Council Instruction
ACC : Army Cyclist Corps
AD : (or Art. Dpt) Artillery Depot
ADAPS : Assistant Director Army Postal Services
ADC : Aide de Camp
ADGT : Assistant Director-General of Transportation
ADL : Assistant Director of Labour
ADLR : Assistant Director of Light Railways
ADMS : Assistant Director Medical Services
ADOS : Assistant Director Ordnance Services
ADRT : Assistant Director Railway Traffic
ADS : Advanced Dressing Station
ADTN : Assistant Director Transportation
ADVS : Assistant Director Veterinary Services
AEC : 9or A. Emp. Coy) Area Employment Company
AF : Army Form
AFA : Army Field Artillery, and Australian Field Artillery
AG : Adjutant General
AGS : Army Gymnastic Staff
AIF : Australian Imperial Force
AIS : Assistant Inspector of Searchlights
AMFO : Assistant Military Forwarding Officer
AMLO : Assistant Military Landing Officer
AMO : Administrative Medical Officer
AMS : Assistant Military Secretary
ANZAC : Australian and New Zealand Army Corps
AO : Army Order
AOC : Army Ordnance Corps
AOD : Army Ordnance Department
AP : Armour Piercing (ammunition)
APC : Army Pay Corps and Assistant Principal Chaplain
APM : Assistant Provost Marshal
APO : Army Post Office
AQMG : Assistant Quartermaster-General
ARMW : Army Reserve Munition Worker
ARD : Alberta Reinforcement Depot
ARP : Ammunition Refilling Point
ARS : Advanced Regulating Station
ASC : Army Service Corps
ASD : Army Schools Department
ASO : Area Searchlight Officer
ASP : (or Amm. Sub. Pk) Ammunition Sub-Park
AT : Army Troops
AVC : Army Veterinary Corps
BAC : Brigade Ammunition Column
BAPO : Base Army Post Office
BC : Battery Commander or Base Commandant
BCA : Battery Commander’s Assistant
Bdmr : Bandmaster
BG : Broad Gauge (railway)
BGGS : Brigadier-General General Staff
BGRA : Brigadier-General Royal Artillery
BL : Breech Loading
BLC : Breech Loading  Converted
BM : Brigade Major
BOR : British Other Rank
BRCS : British Red Cross Society
BSM : Battery Sergeant-Major
BWI : British West Indies Regiment
BWM : British War Medal
CB : Confinement to Barracks (punishment) and Counter-Battery
CBSO : Counter-Battery Staff Officer
CC : Confined to Camp (punishment)
CCCC : Cape Colony Cyclist Corps
CCD : Commander of Coast Defences
CCRA : Corps Commander Royal Artillery
CCS : Casualty Clearing Station
CDS : Corps Dressing Station
CE : Chief Engineer
CEF : Canadian Expeditionary Force
CEPC : Chief Engineer Port Construction
CF : Chaplain to the Forces
CFC : Canadian Forestry Commission
CGS : Chief of General Staff
CHA : Commander Heavy Artillery
CHDAVC : Convalescent Horse Depot Army Veterinary Corps  
CID : Committee of Imperial Defence
CIGS : Chief of the Imperial General Staff
CLC : Chinese Labour Corps
CLLE : Charger-Loading Lee-Enfield rifle
CLLM : Charger-Loading Lee-Metford rifle
CLRO : Corps Light Railway Officer
CME : Chief Mechanical Engineer
CMO : Court-Martial Officer
CMP : Corps of Military Police
CO : Commanding Officer, Conscientious Objector  
COO : Chief Ordnance Officer
CP : Censorship & Publicity
Cpl : Corporal (rank)
CQMS : Company Quartermaster Master Sergeant
CRA : Commanding Royal Artillery
CRCE : Chief Railway Construction Engineer
CRE : Commanding Royal Engineers
CRO : Corps Roads Officer
CSIC : Cadet School Infantry Company
CSM : Company Sergeant Major
CT : Communication Trench
CVBC : Cape Volunteer Bearer Corps
D of A : Director of Artillery
DA : Divisional Artillery
DAA : Director of Army Accounts
DAAG : Deputy Assistant Adjutant General
DAC  - Divisional Ammunition Column
DACG : Deputy Assistant Chaplain General
DADAPS : Deputy Assistant Director Army Postal Services
DADGR&E : Deputy Assistant Director of Graves Registration and Enquires
DADGT : Deputy Assistant Director-General of Transportation
DADL : Deputy Assistant Director of Labour
DADMS : Deputy Assistant Director Medical Services
DADOS : Deputy Assistant Director Ordnance Services
DADPS : Deputy Assistant Director Postal Services
DAD Roads : Deputy Assistant Director of Roads
DAD Sigs : Deputy Assistant Director of Signals
DADRT : Deputy Assistant Director Railway Traffic
DADS : Deputy Assistant Director Supplies
DADT : Deputy Assistant Director Transport
DADW : Deputy Assistant Director of Works
DAG : Deputy Adjutant General
DAMS : Deputy Assistant Military Secretary
DAP : Divisional Ammunition Park
DAPC : Deputy Assistant Principal Chaplain
DAPS : Director of Army Postal Services
DAQMG : Deputy Assistant Quartermaster General
DA & QMG : Deputy Adjutant and Quartermaster General
DBC : Director of Barrack Construction
DCIGS : Deputy Chief of the Imperial General Staff
DCM : Distinguished Conduct Medal
DDAPS : Deputy Director of Army Postal Services
DCM : District Court-Martial
DDGMR : Deputy Director-General Military Railways or Movements and Railways
DDGT : Deputy Director-General of Transportation
DDIWT : Deputy Director Inland Waterway Transport
DDMS : Deputy Director Medical Services
DDOS : Deputy Director Ordnance Services
DDRT : Deputy Director Railway Traffic
DD S and T : Deputy Director Supplies and Transport
DD Sigs : Deputy Director of Signals
DDTN : Deputy Director of Transportation
DDVS : Deputy Director Veterinary Services
DDW : Deputy Director of Works
DEOS : Director of Equipment and Ordnance Stores
DFC : Distinguished Flying Cross
DFS : Director of Financial Services
DFW : Director of Fortifications and Works
DGAMS : Director-General, Army Medical Services
DGAVS : Director-General, Army Veterinary Services
DGNS : Director-General National Service
DGO : Divisional Gas Officer
DGTF : Director-General of the Territorial Force
DIL : Dangerously Ill List
DIWD : Director Inland Waterways and Docks
DIY : Derbyshire Imperial Yeomanry
DLR : Director of Light Railways
DM : Director of Mobilisation
DMO : Director of Military Operations
DMS : Director of Medical Services, also Deputy Military Secretary
DMT : Director of Military Training
DNTO : Divisional Naval Transport Officer
DORA : Defence of the Realm Act
DORE : District Office Royal Engineers
DOS : Director of Ordnance Services
DP : Drill Purpose
DPS : Director of Personal Services
DPW : Director of Prisoners of War
DQMG : Deputy Quartermaster-General
DR :  Despatch Rider
DR :  Despatch Rider
DRF : Depression Range-Finder
DRG&E : Director of Graves Registration and Enquires
DRLS : Despatch Rider Letter Service
D Rlys : Director of Railways
DRO : Director of Recruiting and Organisation
DRT : Director Railway Traffic
DSC : Distinguished Service Cross (a naval decoration)
DSD : Director of Staff Duties
DSM : Distinguished Service Medal (a naval decoration)
DSO : Distinguished Service Order
DSQ : Director of Supplies and Quartering
DTM : Director of Transport and Movements
DTMO : Divisional Trench Mortar Officer
DTN : Director of Transportation
DW : Director of Works
EBSVR : East Bengal State Volunteer Rifles
EEF : Egyptian Expeditionary Force
EFC : Expeditionary Force Canteen
EinC : Engineer in Chief
ELC : Egyptian Labour Corps
E&M : Electrical and Mechanical
EMO : Embarkation Medical Officer
FANY : First Aid Nursing Yeomanry
FAO : Forward Area Officer (Light Railways)
FAU : Friends Ambulance Unit
FGCM : Field General Court-Martial
FLC : Fijian Labour Contingent (later Corps)
FOO : Forward Observation Officer
FP : Field Punishment
FPO : Field Post Office
FSC : Field Survey Company
FSL : Field Searchlight
FSM : Field Service Manual
FSR : Field Service Regulations
FWD : Four Wheel Drive
GCM : General Court-Martial
GHQ : General Headquarters
GMP : Garrison Military Police
GOC : General Officer Commanding
GOCinC : General Officer Commanding-in-Chief
GRC : Graves Registration Commission
GRO : General Routine Order
GRU : Graves Registration Unit
GS : General Service and General Staff
GSO : General Staff Officer
GSW : Gunshot Wound
HA : Heavy Artillery
HAR : Heavy Artillery Reserve
HBMGC : Heavy Branch Machine Gun Corps (later Tank Corps)
HE : High Explosive
HPD : Home Postal Depot
HS : Home Service
HSC : Hospital Ship Case (medical)
HT : Horse Transport
HV : High Velocity
IA : Indian Army
IAF : Independent Air Force
IE : Illegal enlistment
IGC : Inspector-General of Communications
IGT : Inspector-General of Transportation
IHL : Imprisonment with Hard Labour
IO : Intelligence Officer
IOM : Inspector of Ordnance Machinery
IOR : Indian Other Rank
IS : Inspector of Searchlights
IWGC : Imperial War Graves Commission
IWT : Inland Water Transport
IW&D : Inland Waterways and Docks
JAG : Judge Advocate General
KR : King’s Regulations
L/C or L/Cpl: Lance Corporal
LEE : London Electrical Engineers
LO : Liaison Officer
LofC : Lines of Communication
LR : Local Reserve
MAC : Motor Ambulance Convoy
MB : Medical Board
MC : MIlitary Cross
MDS : Main Dressing Station
MEF : Mediterranean Expeditionary Force
MFD : Military Forwarding Department
MFO : Military Forwarding Officer
MFP : Military Foot Police
MGC : Machine Gun Corps
MGGS : Major General General Staff
MGO -  Master-General of the Ordnance
MGRA : Major General Royal Artillery
MGS : Machine Gun School
MLO : Military Landing Officer
MM : Military Medal
MMGC : Motor Machine Gun Corps
MML : Manual of Military Law
MMP : Military Mounted Police
MPI : Mean Point of Impact
MPSC : Military Police Staff Corps
MS : Military Secretary
MSM : Meritorious Service Medal
MT : Mechanical Transport
MVC : Motor Volunteer Corps
MVS : Mobile Veterinary Section
NACB : National Army Catering Board
NCC : Non-Combatant Corps
NTO : Naval Transport Officer
NYD : Not Yet Diagnosed (medical term)
NYDN : Not Yet Diagnosed Nervous (medical term for suspected shell shock)
OC : Officer Commanding, Officer Cadet
OR : Other Rank
ORS : Orderly Room Sergeant
OTC : Officers Training Corps
PB : Permanent Base (medical)
PBI : Poor Bloody Infantry (colloquial)
P & BT : Physical and Bayonet Training
PC : Principal Chaplain (non Church of England)
PM : Provost Marshal
PNTO : Principal Naval Transport Officer
POW : Prisoner of War
PPCLI : Princess Patricia's Canadian Light Infantry
psc : Passed Staff College
Pte : Private (rank)
PU : Permanently Unfit (medical)
PUO : Pyrexia of Unknown Origin (medical term usually applied to Trench Fever)
QF : Quick Firing
QMAAC : Queen Mary’s Army Auxiliary Corps
QMG : Quartermaster General
QMS : Quartermaster Sergeant
Qs : Qualified for Staff
RAF : Royal Air Force
RAFA : Royal Australian Field Artillery
RAGA : Royal Australian Garrison Artillery
RAP : Regimental Aid Post
RCE : Railway Construction Engineer
RCO : Railway Control Officer
RDC : Royal Defence Corps
REPS : Royal Engineers Postal Section
RFA : Royal Field Artillery
RFC : Royal Flying Corps
RGA : Royal Garrison Artillery
RH - Railhead
RHA : Royal Horse Artillery, and Reserve Heavy Artillery
RM : Riding Master, and Royal Marines
RMA : Royal Marine Artillery
RMLC : Royal Marine Labour Corps
RMLI : Royal Marine Light Infantry
RNAS : Royal Naval Air Service
RND : Royal Naval Division (63 Div)
RO : Recruiting Officer
ROD : Railway Operating Division
ROO : Railway Ordnance Officer
RP : Rules of Procedure, Regimental Police, Refilling Point
RSM : Regimental Sergeant Major
RSO : Railhead Supply Officer
RTC : Reserve Training Centre
RTE : Railway Transport Establishment
RTO : Railway Transport Officer (later Railway Traffic Officer)
RTU : Returned to Unit
S - Service
SAA : Small Arms Ammunition
SANLC : South African Native Labour Corps
SC : Staff Captain
SCF : Senior Chaplain to the Forces
SD : Staff Duties
SGS : Surveyor-General of Supply
Sgt : Sergeant (rank)
SIW : Self-Inflicted Wound
Sjt : Serjeant (rank)
SLR : Superintendent of Light Railways
SMLE : Short Magazine Lee-Enfield
SOS : Struck off strength. Also used in usual sense (of emergency).
SP : Strongpoint
SPT : (preceding a man's number) Sportmen's Battalion Royal Fusiliers
SR : Special Reserve
SRS : Sound Ranging Section
SSM : Squadron Sergeant Major (cavalry)
STK : (preceding a man's number) Stockbroker's Battalion Royal Fusiliers
TAT : Temporary Ambulance Train
TB : Temporary Base (medical)
TC : Tank Corps
TCO : Train Conducting Officer
TDO : Telephone Dug-out
TEE : Tyne Electrical Engineers
TF : Territorial Force
TM : Trench Mortar
TMB : Trench Mortar Battery
TO : Transport Officer
TOS : Taken on strength
TR : Training Reserve
TRB : Training Reserve Brigade
TSM : Troop Sergeant Major (cavalry)
VAD : Voluntary Aid Detachment
VADGS : Voluntary Aid Detachment General Service
VC : Victoria Cross
VO : Veterinary Officer
VTC : Volunteer Training Corps
WAAC : Women’s Army Auxiliary Corps (later QMAAC)
WD : War Department
WE : War Establishment
WIR : West India Regiment
WO : War Office
WWCS : Walking Wounded Collecting Station
YOC : Young Officers Company
YS : Young Soldier