We’re fortunate to include a great range of experience and interests among our membership. However, the knowledge gap between the services, generations, professionals and hobbyists can vary widely.

Click here for sources and other institutions’ glossaries.

Please note that formations may differ in size by country, service and specialism.

1SL – First Sea Lord (1904-present)

2iC – Second-in-Command

2Lt / 2nd Lt – Second Lieutenant

2SL – Second Sea Lord

AA – Anti-aircraft

AAA – Anti-aircraft artillery

AAC – Army Air Corps (1942-49, 1957-present)

AAS / AAC – Army Apprentices Schools later Army Apprentices Colleges (16 institutions open between 1924 and 2004)

AB – Able-bodied Seaman

ABM – Anti-Ballistic Missile

ABU – Armoured Beach Unit. Advance group on a beach landing to prepare and assist with the landing

ACC – Army Catering Corps (1941-93)

ACF – Army Cadet Force

AdC – Aide-de-Camp

Adm – Admiral

AEW – Airborne Early Warning

AFC – Air Force Cross

AGC – Adjutant General’s Corps (1992-present)

Air Group – An air force unit consisting of at least two squadrons. Commanded by a Group Captain

Air Wing – An air force unit consisting at least two groups. Commanded by a Wing Commander

ANZAC – Australian and New Zealand Army Corps

APC – Armoured Personnel Carrier. Wheeled or tracked vehicle to transport troops to a forward area and evacuate wounded

APTC – Army Physical Training Corps (1860-present)

AQMS – Artificer Quartermaster Sergeant (REME WO2)

Art – Artillery

ASM – Artificer Sergeant Major (REME WO1)

AWOL – Absent without leave

Battalion – A military unit consisting of 300-1,200 soldiers subdivided into a number of companies. Commanded by a Lieutenant Colonel.

Battery – An artillery unit typically consisting of six guns and their artillerymen and equipment. Equivalent of an infantry company.

BEF – British Expeditionary Force

BEM – British Empire Medal

BER – Beyond economic repair. When an item costs more to repair than to replace

BLR – Beyond local repair. When an item that is repairable but not by the unit holding it

Bn – Battalion

Bombardier – Corporal, Royal Artillery; Bomb aimer, RAF

Brig – Brigadier

Brigade – A major tactical military unit made up of three-to-six battalions, or two regiments. Commanded by a Colonel, Brigadier, Brigadier-General or Major-General.

BRNC – Britannia Royal Naval College, Dartmouth

Btry – Battery

BW – Biological weapons/warfare

C2 – Command and control

C3I – Command, control, communications and intelligence

Capt – Captain

CAS – Chief of the Air Staff (1918-present)

Cav – Cavalry

CBRN – Chemical, Biological, Radiological and Nuclear

CCF – Combined Cadet Force

Cdo – Commando

Cdr – Commander

Cdre – Commodore

CDS – Chief of the Defence Staff (1959-present)

CGS – Chief of the General Staff (1904-09 and 1964-present)

CIGS – Chief of the Imperial General Staff (1909-64)

C-in-C – Commander-in-Chief

CIWS – Close-in weapons system

CO – Commanding Officer

COBR – Cabinet Office Briefing Rooms

COBRA – Cabinet Office Briefing Room A

COD – Command Ordnance Depot. A depot suppling stores to the Army at home and overseas

CofS – Chief of Staff

Col – Colonel

Comb. Ops – Combined Operations. When two or more of the armed services operate under a single command

Company – A military unit made up of two or more platoons (30-250 soldiers). Commanded by a Captain or Major.

Continuity IRA / CIRA – Continuity Irish Republican Army. Nationalist paramilitary group (1986-present)

Corps – A major military unit made of two-to-five divisions (20,000-80,000 soldiers). Commanded by a Lieutenant General.

Corporal of the Horse – Sergeant, Household Cavalry

Cpl – Corporal

CQB – Close quarters battle

CSgt – Colour Sergeant

CSM – Company Sergeant Major

CSN – Confederate States Navy (1861-65)

CSS – Confederate States Ship

CVN – Nuclear-powered aircraft carrier

CW – Chemical weapons/warfare

CWGC – Commonwealth War Graves Commission (1960-present)

DCLI – Duke of Cornwall’s Light Infantry, British infantry (1881-1959)

DCM – Distinguished Conduct Medal

DDG – Guided-missile destroyer

DERR – Duke of Edinburgh’s Royal Regiment, British infantry (1959-94)

DFC – Distinguished Flying Cross

Division – A main military unit made up of multiple regiments or brigades (6,000-25,000 soldiers). Commanded by a Major General.

DLI – Durham Light Infantry, British infantry (1881-1968)

DoD – U.S. Department of Defense

Dragoons – Originally, mounted infantry named for their use of carbines (fire-breathing “dragons”).

DSC – Distinguished Service Cross

DSM – Distinguished Service Medal

DSO – Distinguished Service Order

DZ – Drop zone

ECM – Electronic countermeasures

EOD – Electronic Ordnance Disposal

FAA – Fleet Air Arm

FFG – Guided-missile frigate

FIDF – The Falkland Islands Defence Force (1892-1920, 1920-82, 1983-present)

FM – Field Marshal

FOB – Forward Operating Base

FOCAS – Flag Officer, Carriers and Amphibious Ships (1970-79)

FUSILIERS – The Royal Regiment of Fusiliers, British infantry (1968-present)

GC – George Cross

GCHQ – Government Communications Headquarters

Gen / Gnrl – General

GHQ – General Headquarters

GM – George Medal

GPMG – General purpose machine gun

GREN GDS – The Grenadier Guards, British infantry (1656-present)

GSC – The General Service Corps (1942-present)

HAC – Honorable Artillery Company, British artillery (1537-present)

HLI – Highland Light Infantry, British infantry (1881-1959)

HMG – Her/His Majesty’s Government

HMNB – Her/His Majesty’s Naval Base

HMS – Her/His Majesty’s Ship

HQ – Headquarters

Hussars – Light cavalry.

IG – The Irish Guards, British infantry (1900-present)

IJN – Imperial Japanese Navy (1868-1945)

Inf – Infantry

Int Corps – The Intelligence Corps (1914-29, 1940-present)

IRA – Irish Republican Army. A name used by multiple nationalist paramilitary groups since 1919

IWGC – Imperial War Graves Commission (1917-60)

IWM – Imperial War Museum

JHC – Joint Helicopter Command

JTF – Joint Task Force

KIA – Killed in action

KOSB – King’s Own Scottish Borderers, British infantry (1689-2006)

KOYLI – King’s Own Yorkshire Light Infantry, British infantry (1881-1968)

KRH – The King’s Royal Hussars, British cavalry(1992-present)

Kriegsmarine – German Navy (1935-45)

KRRC – King’s Royal Rifle Corps, British infantry (1756-1966)

KSLI – King’s Shropshire Light Infantry, British infantry (1881-1968)

LAC – Leading Aircraftsman

LAD – Light aid detachment. A REME detachment posted to an army unit to do first line repairs. Size depends on the unit: a sergeant plus 6 or 7 men, or a captain and over 100 men in an armoured regiment

LANCS – The Duke of Lancaster’s Regiment, British infantry (2006-present)

LCM – Landing Craft Mechanised. Carried in the dock of an LPD

LCpl – Lance Corporal

LCVP – Landing craft vehicle and personal. Carried on davits in-board on the side of an LPD

LD – The Light Dragoons, British cavalry(1992-present)

LG – The Life Guards, British cavalry(1922-present)

LPD – Landing Platform Dock. Also known as assault ships (e.g. HMS Albion and HMS Fearless)

LRDG – Long Range Desert Group (1940-45)

LSL – Landing Ship Logistic. Round Table class ships operated by the RFA (e.g. Sir Bedivere, Sir Galahad, Sir Geraint, Sir Lancelot, Sir Percivale, Sir Tristram)

LST –  Landing Ship Tank

Lt – Lieutenant

Lt Col – Lieutenant Colonel

Lt Gen – Lieutenant General

Lt Inf – Light Infantry

Luftwaffe – German Air Force (1933-46)

Maj – Major

Maj Gen – Major General

MBT – Main Battle Tank

MC – Military Cross

MEDEVAC – Medical Evacuation

MERC / MERCIAN – The Mercian Regiment, British infantry (2007-present)

MEXE – Military Engineering Experimental Establishment (1946-70)

MEXE float – Pontoon float carried on the outside of the hull of an LSL. Can be driven by outboard or used as a jetty

MGC – Machine Gun Corps

Mid – Midshipman

MM – Military Medal

MoD – Ministry of Defence

MP – Military Police (see RMP)

NAAFI – Navy, Army and Air Force Institute

NAM – National Army Museum

NATO – North Atlantic Treaty Organisation

NCO – Non-Commissioned Officer

New IRA – New Irish Republican Army. Nationalist paramilitary group (2012-present)

OC – Officer Commanding

OiC – Officer in Command

OIRA – Official Irish Republican Army. Nationalist paramilitary group (1969-72/late-1990s)

OP – Observation Post

OpSec – Operational Security

OTC – Officer Training Corps

PARA – The Parachute Regiment, British airborne infantry (1942-present)

PJHQ – Permanent Joint Headquarters

PLA – People’s Liberation Army (China)

PLAN – People’s Liberation Army Navy (China)

POW – Prisoner of War

PPCLI – Princess Patricia’s Canadian Light Infantry (1914-present)

Provisional IRA / PIRA – Provisional Irish Republican Army. Nationalist paramilitary group (1969-1997/2005)

PSNI – Police Service of Northern Ireland (2001-present)

PWRR – Princess of Wales’s Royal Regiment, British infantry (1992-present)

QARANC – Queen Alexandra’s Royal Army Nursing Corps (1949-present)

QDG – 1st The Queen’s Dragoon Guards, British cavalry. Also known as the Welsh Cavalry (1959-present)

QF – Quick firing

QM – Quartermaster

QOY – The Queen’s Own Yeomanry, British cavalry (1971-present)

QRF – Quick Reaction Force

QRH – The Queen’s Royal Hussars, British cavalry (1993-present)

R ANGLIAN – The Royal Anglian Regiment, British infantry (1964-present)

R IRISH – The Royal Irish Regiment, British infantry (1992-present)

R SIGS / R SIGNALS – The Royal Corps of Signals (1920-present)

R WELSH – The Royal Welsh, British infantry (2006-present)

RA – The Royal Regiment of Artillery (1716-present)

RAC – Royal Armoured Corps, British cavalry

RAdm – Rear Admiral

RAF – Royal Air Force (1918-present)

RAMC – The Royal Army Medical Corps (1898-present)

RANGER – The Ranger Regiment, British infantry (2021-present)

RAVC – The Royal Army Veterinary Corps (1796-present)

RCM – Regimental Corporal Major. WO1, Household Cavalry

RCT – Royal Corps of Transport (1965-93)

RDG – The Royal Dragoon Guards, British cavalry (1992-present)

RE – The Corps of Royal Engineers (1716-present)

Real IRA / RIRA – Real Irish Republican Army. Nationalist paramilitary group (1997-2012)

Regiment – A military unit whose role and size varies by country and/or function. Often made up of multiple battalions. Commanded by a Lieutenant Colonel.

REME – The Corps of Royal Electrical and Mechanical Engineers (1942-present)

RFA – Royal Field Artillery; Royal Fleet Auxiliary

RFC – Royal Flying Corps (1912-18)

RG – The Royal Gibraltar Regiment (1958-present)

RGBW – Royal Gloucestershire, Berkshire & Wiltshire Regiment, British infantry (1994-2007)

RGJ – Royal Green Jackets, British infantry (1966-2007)

RGR – The Royal Gurkha Rifles, British infantry (1994-present)

RHA – Royal Horse Artillery

RHG/D – Royal Horse Guards and 1st Dragoons, British cavalry. Also know as the Blues and Royals (1969-present)

RHQ – Regimental Headquarters

RIFLES – The Rifles, British infantry (2007-present)

RLC – The Royal Logistic Corps (1993-present)

RM – Royal Marines (1664-present)

RMA – Royal Military Academy, Sandhurst

RMLI – Royal Marine Light Infantry

RMP – Royal Military Police (1926-present)

RMR – Royal Marines Reserve

RN – Royal Navy

RNAS – Royal Naval Air Service (1914-18); Royal Naval Air Station

RNR – Royal Naval Reserve

RoE – Rules of Engagement

RP – Regimental Police. Only have authority over regimental personnel

RSM – Regimental Sergeant Major

RSME – Royal School of Military Engineering, Chatham

RTR – Royal Tank Regiment, British cavalry (1917-present)

RUC – Royal Ulster Constabulary (1922-2001)

RWY – The Royal Wessex Yeomanry, British cavalry (1971-present)

RY – The Royal Yeomanry, British cavalry (1967-present)

SAM – Surface-to-Air Missile

SAR – Search and Rescue

SAS – Special Air Service (1941-present)

SASC – The Small Arms School Corps (1853-present)

SBS – Special Boat Squadron (1940-present)

SCM – Squadron Corporal Major. WO2, Household Cavalry

SCOTS – The Royal Regiment of Scotland, British infantry (2006-present)

SCOTS DG – The Royal Scots Dragoon Guards, British cavalry (1971-present)

SeAL – Sea, Air, Land

SG – The Scots Guards, British infantry (1642-present)

Sgt – Sergeant

SIB – Special Investigation Branch. Part of the Royal Military Police

SitRep – Situation Report

SF – Special Forces

SLR – Self-loading rifle

SMG – Sub-machine gun

SMHS – Salisbury Military History Society (2019-present)

SNIY – The Scottish and North Irish Yeomanry, British cavalry (2014-present)

SOE – Special Operations Executive (1940-46)

SP – Shore Patrol. Naval patrol used when a ship is in port to keep order on shore. Normally consisting of a Petty Officer and three Ratings

SP gun – Self propelled gun. Often on tracks and armoured with a turret that has limited travers of only a few degrees

Sqn – Squadron

Squadron (army) – A sub-unit of a cavalry, engineer or armoured regiment. Equivalent of an infantry company

Squadron (air force) – A unit consisting of three or four flights (12-24 aircraft). Commanded by a Squadron Leader or Wing Commander

SRR – The Special Reconnaissance Regiment (2005-present)

STOVL – Short-Take-Off and Vertical Landing

TA – Territorial Army, the UK’s army reserve (1921-1967 and 1979-2014)

TAVR – Territorial and Army Volunteer Reserve (1967-1979)

TCV – Troop carrying vehicle. Variants of the Bedford QL fitted with padded seats. (1941-60s)

UAS – University Air Squadron

UAV – Unmanned Aerial Vehicle

UDA – Ulster Defence Association. Loyalist paramilitary group (1971-94/2007)

UDR – Ulster Defence Regiment (1970-92)

UKLF – United Kingdom Land Forces. Controls British Army worldwide

UN – United Nations

URNU – University Royal Naval Unit

USAAF – United States Army Air Force

USAF – United States Air Force

USMC – United States Marine Corps (1798-present)

USN – United States Navy

USS – United States Ship

UVF – Ulster Volunteer Force. Loyalist paramilitary group (1966-1994/2007)

UW – Urban Warfare

UXB – Unexploded bomb

VAdm – Vice Admiral

VC – Victoria Cross

WAAC – Women’s Auxiliary Army Corps

WAAF – Women’s Auxiliary Air Force

Waffen-SS – Armed branch of the Nazi Party’s Schutzstaffel (1933-45)

Wehrmacht – German armed forces (1935-45)

WG – Welsh Guards, British infantry (1915-present)

Wing – An air force unit consisting at least two groups. Commanded by a Wing Commander

WMD – Weapons of Mass Destruction

WO1 – Warrant Officer class 1. Warrant Officers are the highest rank of NCOs in the British Army

WO2 – Warrant Officer class 2. Warrant Officers are the highest rank of NCOs in the British Army

WRNS – Women’s Royal Naval Service

WW1 – World War One (1914-18)

WW2 – World War Two (1939-45)

XO – Executive Officer

Yeomanry – Reserve cavalry

YORKS – The Yorkshire Regiment, British infantry (2006-present)