| Admiralty | a government department responsible for the command of the Royal Navy in the Kingdom of Great Britain, from 1801 to 1964, the United Kingdom and former British Empire |
| airstrike | a military attack involving aircraft |
| Allies | in WW1, the powers of the Triple Entente (France, Russia and the UK) together with their allied nations; in WW2, a military coalition of the UK, US, Soviet Union and China together with their allied nations. |
| amnesty | a period of time during which people can admit to a crime or give up weapons without being punished |
| amputation | to surgically cut all or part of an arm or leg because it's seriously injured or diseased |
| anglicise | to change something so that it resembles or becomes part of the English culture or language |
| Anglo-Celtic | an inhabitant of Australia who was or whose ancestors were born in the British Isles |
| annex | To seize and take control of land or another country |
| anti-Semitism | hostility to and prejudice against Jewish people. |
| Anzac spirit | the spirit of courage, endurance, and self-sacrifice thought to be typical of the Australian soldiers during the Gallipoli Campaign |
| Anzacs | the soldiers serving with the Australian and New Zealand Army Corps (ANZAC) |
| apartheid | an historical political system in South Africa where people were divided into racial groups and kept apart by law |
| armistice | an agreement between opposing governments or military forces to suspend conflict and discuss peace terms; a truce |
| armour | tanks and other armoured military vehicles used in battle |
| armoury | a place where weapons and military equipment are stored; or all the weapons and military equipment a country has |
| arms race | a situation in which two countries or groups of countries are continually trying to get more and better weapons than each other |
| arsenal | a large collection of weapons and military equipment |
| artillery | large, powerful guns that are transported on wheels and used by an army, or the section of an army trained to use large, powerful guns - also 'artillerymen or gunners' |
| assassinate | to murder a person as a political act |
| assault | a strong attack made on an area held by the enemy |
| atrocity | an extremely cruel act that typically involves physical violence or injury |
| autonomy | the control or government of a country or group by itself rather than by others |
| auxiliary | helping or supporting |
| Axis, the | in World War II, the alliance of Nazi Germany, Fascist Italy and Japan |
| ballast | a substance used in ships and submarines to make them heavier and more stable, such as water, sand or iron |
| barracks | a building or group of buildings used to accommodate military personnel |
| barrage | continuous firing on an area with large guns, tanks or naval guns |
| battery | a set of artillery pieces, guns or mortars kept together in one place |
| battery ranging | an artillery method that attempts to identify the distance and range of enemy artillery from own artillery |
| bayonet | a long sharp blade attached to the end of a rifle, intended as a weapon but used for other tasks, such as opening cans of rations |
| beachhead | an area of land next to the sea or a waterway gained by an attacking force and from where it can try to advance inland |
| belligerent | the countries or groups that are fighting each other in a war |
| billet | a private house, barn or other accommodation that provides temporary lodging to soldiers during a war |
| bite and hold | seize a small piece of territory within artillery range and hold it before trying to seize another small piece of territory |
| bivouac | a temporary camp made by soldiers or mountain climbers |
| black market | a system in which goods are sold and bought illegally, often due to a controlled or rationed market for such goods |
| blockade | an action to block or cut off a nation's sea lines of communications, especially of an individual port by the use of sea power |
| bombardment | attacking a place or target with continuous heavy gunfire or bombs |
| bonzer | an old-fashioned Australian and New Zealand slang term for 'excellent' |
| breach | to break through a heavily defended section of an enemy's defences |
| breastwork | a temporary defensive work, such as a breast-high wall or mound of sandbags, also known as the 'rampart'; the 'parapet' is the top part of the breastwork |
| British | describes an object or a subject (person, colony, dominion) belonging to either Great Britain, the United Kingdom or the British Empire |
| British Empire | the United Kingdom and the former territories under its control, which reached its greatest extent at the end of World War I |
| bully beef | tinned corned beef |
| cacolet | a seat or bed fitted to a camel or mule for carrying sick or wounded people |
| cadet | a student or young person undergoing military training, usually before full entry to the services, especially for officer status |
| calibre | the width of the inside of a gun's barrel |
| casualty | a person who is injured or killed in a war |
| Casualty Clearance Post (CCP) | a safe area within a conflict zone or disaster site, for triage and emergency treatment of casualties before they are transported elsewhere for further care. |
| Catafalque | a temporary raised platform on which a body lies in state before or during a funeral |