| tourniquet | a strip of cloth tied tightly around an injured arm or leg to stop bleeding |
| tow | a towboat or tug used for pushing a barge or group of barges |
| transport | a military vehicle, especially a ship or plane, that's used to carry soldiers or equipment |
| traverse | a protective bank or other barrier across a trench |
| treaty | a written agreement between countries to show they agree a particular action or to help each other |
| triage | the practice of sorting battle casualties (sick and wounded people) into categories of priority for treatment |
| troopship | a ship that carries a large number of soldiers from one place to another |
| truce | an agreement between 2 parties to stop fighting for a short time |
| trusteeship | administration or government of a territory by a foreign country under the supervision of the Trusteeship Council of the United Nations |
| Turk | a person from the principal ethnic group of Türkiye or, formerly, the Ottoman Empire; a Turkic-speaking person |
| Türkiye | the centre of the Ottoman Empire; became a republic in 1923 |
| U-boat | a German submarine |
| ultimatum | a final offer issued in negotiations, the rejection of which can lead to a break in relations and some action |
| undercarriage | the part of a plane, including the wheels, that provides support when it is on the ground and when it is landing or taking off |
| unexploded ordnance | any sort of military ammunition or explosive ordnance that has failed to function as intended |
| United Kingdom (UK) | refers to the United Kingdom of Great Britain and Ireland from 1 January 1801 to 5 December 1922, or the United Kingdom of Great Britain and Northern Ireland from 5 December 1922 |
| upper class | describes a group of people in a society who have the highest economic or social status |
| vanguard | the part of a military force that goes into battle first; 'van' for short |
| veteran | a person who served in the armed forces of their country during a war or peacekeeping mission |
| Victoria Cross (VC) | the highest decoration for gallantry in the face of the enemy awarded to members of the British and Commonwealth armed forces |
| Viet Cong | a communist guerrilla force that sought to overthrow the South Vietnamese government, later allied with North Vietnam |
| war cry | a rallying cheer or slogan shouted by combatants in battle |
| warlike service | Types of service determined by the Minister for Defence that may include military activities where the application of force is authorised to pursue specific military objectives and there is an expectation of casualties, including a declared state of war, conventional combat operations and peace enforcement operations. |
| weight of fire | a measure of the quantity, density and intensity of artillery fire used to attack a target (see also 'fire-effect') |
| White Australia policy | a term for the Immigration Restriction Act 1901 and its amendments, laws that prevented permanent migration of non-European peoples, especially Asians (mostly Chinese) and Pacific Islanders |
| wilco | an expression in signalling that indicates compliance with a message just received |
| wireless | a telegraphy system that sends messages over a distance by radio signals |