Unfortunately, it's necessary to understand war vocabulary if you want to follow the news or study history in English.
This page gives the basic meanings of several different categories of military vocabulary:
The words below are nouns (n.) unless they have a note that they are adjectives (adj.) or verbs (vb.). Many have a singular form ending in ‘y’ with a plural ending in ‘-ies’: ally/allies, army/armies, enemy/enemies, navy/navies, sentry/sentries, etc.
Military is an adjective or noun meaning related to a nation’s armed forces.
Civilian (also adj. or n.) means someone or something not in the military.
Enemies or opponents are nations or people fighting against a country.
Allies are nations on the same side, supporting each other.
Neutral countries are nations that are not involved on either side.
War is a violent conflict between two or more groups (usually nations).
A battle is a violent encounter between opposing sides, often as part of a larger war.
Combat is periods of actual fighting. (Before antibiotics, more soldiers died of infected wounds than during active combat.)
A revolution is a struggle between large groups that leads to a major change in government and society. (Often those who have been powerless are trying to take power away from the current dominant class.)
Rebellions, revolts and uprisings all aim to change the government, too. But they don't overthrow class relations and social arrangements as a revolution does.
(Some historians consider the American ‘Revolution’ an independence struggle rather than a revolution. That's debated because it did lead to major changes in social organization.)
A civil war is a war between two (or more) groups within one nation. (In the United States, people in the north talk about the civil war in the U.S. between 1861 and 1865. In the past, many Southerners objected to that term. They felt the Confederate states had left the Union and were no longer part of one nation.)
A coup d’état is a government overthrow, often by the military or a small group of conspirators
To fortify something (a vb.) is to make it strong. Forts are buildings with strong walls. They protect important places against attack. (Examples are river crossings, harbors, mountain passes, or other key entry points.) Fortifications are any structures built for protection. They include walls, trenches (ditches to hide in), forts, etc.
To guard (a verb: vb.) is to watch over and protect someone or something. A guard (n.) is the person who does that. A sentry is a military guard keeping watch to prevent enemies from entering a camp, fort, etc.
To retreat (n. or vb.) is to withdraw from (leave) an area in an orderly way. Soldiers often retreat after losing a battle to prevent further losses
An attack is violent aggression against a person or country. (The verb is to attack.)
An invasion is when attackers enter the territory of their enemy to take control of it. (To invade is the verb.)
An invading army can besiege (vb.) a fortified city by surrounding it and trying to cut off its supplies. The intention of a siege (the noun) is to weaken the residents enough to overcome their defenses and capture the city.
A naval blockade (n. or vb.) is similar: ships prevent necessary supplies from reaching a city or country. It can be very effective in countries that depend on trade for food and other basic needs, or for weapons and income to keep fighting. During the American Civil War, a blockade of the South cut off needed supplies as well as income. The South had specialized in producing cotton for export rather than diversifying its economy. So it did not produce the weapons, equipment, and in some parts food needed to get by on its own.
To capture (usually vb.) people or cities is take control of them.
An ambush (n. or vb.) is a trap planned to capture or destroy enemy troops. The side planning the ambush hides most of their troops so that their enemies expect an easy victory. When their enemies attack, the hidden troops come out and overwhelm the enemy forces.
Results of a battle:
Victory is winning a battle (or a war.) Defeat is losing it, and a stalemate occurs when neither side gains much.
Casualties are people killed or injured. Losses can include equipment and positions lost as well as deaths and injuries
Prisoners of war are fighters captured by the opposing side. (They may be imprisoned- kept in prisons. Sometimes the two sides arrange for an exchange of prisoners.)
An army is troops that fight on land: soldiers.
A navy is a nation’s ships and sailors. Navies fight on the seas. (The adjective is naval.)
The Marine Corps (pronounced core) troops are amphibious (able to fight on both land and sea). They often lead the fighting in landings and special operations.
Air Force pilots fly a nation’s aircraft. The Air Force coordinates with the other military services. It collects information on battlefields and enemy positions by aerial reconnaissance. Air Force planes carry paratroopers who will parachute behind enemy lines. The planes also drop bombs and try to shoot down enemy planes.
Historically, armies were divided into infantry (foot soldiers) and cavalry (soldiers on horseback.)
The military forces of a nation are built in two ways. Voluntary enlistment is when people choose to sign up for a term of military service. Conscription ("the draft") is when a nation requires some or all men (or men and women) of certain ages to join the military.
A fleet is a group of ships that travel together. Battleships do the main fighting on the seas.
Aircraft carriers have very large decks to carry airplanes and allow them to take off and land on the deck. The airplanes are used for reconnaissance (discovering enemy positions and numbers) and bombing.
Troop transports carry large numbers of soldiers across the water to the places they intend to fight.
Submarines (often called “subs”) travel underwater to attack ships from beneath without being seen.
As mentioned, aircraft can gather information, bomb enemy positions, fight against enemy aircraft, and carry paratroopers. Helicopters can maneuver, take off, and land in tight spots that airplanes cannot. This makes them very useful for rescue missions.
Tanks are offensive armored vehicles with big guns. They move on tracks connecting the wheels, so they can go into places many trucks could not reach.
Uniforms are the matching outfits worn by members of each service on formal occasions. (See the picture under "Armed Forces.") Historically, they were used in battle as well. They made it easy to identify comrades and enemies in close combat.
Uniforms also make troops easy targets for sharpshooters. So soldiers are more likely to wear camouflage in battle now.
Camouflage is clothing or vehicle coverings that blend with surroundings. It makes it harder for the enemy to see (or aim at) troops or equipment.
Helmets are hard head coverings to protect the head and often the neck.
Armor protects the body (especially the chest, but often also back, arms, legs, and hands.). It can be made of metal pieces fastened together so they allow movement or heavy quilted cloth.
Knights in the Middle Ages often rode into battle almost completed covered in armor. They often had a headpiece that covered the head and face except for narrow openings for eyes, ears, and mouth.
Shields are large oval or rectangular pieces of metal or other firm material. Soldiers held them in from of their bodies and moved them to block swords, spears, or arrows.
All of these except swords, knives, and mines are designed to be used at a distance.
Guns are weapons that shoot metal bullets over a distance. An automatic fires multiple shots without reloading. A rifle, like an automatic, has a long barrel. A pistol is a type of handgun, smaller and easier to carry or to conceal (hide).
The verbs for using guns are ‘to shoot’ or ‘to fire’, so soldiers might hear or be attacked by gunfire or gunshots.
Grenades are hand-held explosive devices. When thrown, they can blow up a vehicle, building, or group of people.
Bombs are large explosive devices that can destroy buildings, people, or even large areas of a city. Heavy bombing of a fort or military position is called a bombardment. (Bomb can also be a vb.)
Land mines are buried devices that explode when someone or something puts weight on them.
Missiles are explosive objects sent to blow up their target. They can be self- or remote-controlled and can even be nuclear.
Torpedoes are missiles fired from ships or submarines or dropped from the air. They explode on impact, to damage or sink ships.
Archers use bows to shoot arrows for much longer distances than spears can travel.
Swords are long sharp weapons used in hand-to-hand (close) combat or from horseback. Knives are similar, but shorter.
Spears (or lances) are long poles with sharp, knife-like tips. Soldiers or horsemen can throw them or use them to strike an enemy from a greater distance than swords. (See the picture with shields under “Equipment.")
Cannons are heavy long metal tubes with a gunpowder-loading mechanism at the end. They shoot iron cannonballs or smaller ammunition like grapeshot or explosive shells from a distance.
They can break down castle or fort walls and knock holes in the side of ships, causing them to sink. They can also kill many soldiers in the field. Cannons were introduced to Europe from China in the Middle Ages. They were still major killers during World War I and II.
A signal is a message sent without words. It can be a hand or body gesture, a light, fire, smoke, or a sound. For example, one signal might be a certain number of gunshots that the sender and receiver have agreed on.
A famous signal in American history was the light flashed from a church tower to tell Paul Revere the way the British were coming. The agreed signal was “one (light flash) if by land, two if by sea.”
Military messages are often sent in code like that. A code is a way to hide a message so enemies cannot understand it if they find it. For example, a simple verbal code might be to say “Jack Robinson.” (It might mean that it's time to act, or that someone has arrived. The important point is that both sender and receiver know what it means-- and no one else does.)
Written codes can be very complicated. Some substitute numbers for letters or certain words for other words. Others use a machine that both parties must have to send or understand the coded message.
Spies are people trying to get information on enemy plans, strength, and positions. They often work in enemy territory. (The singular form is ‘spy,’ which can also be a vb.)
Propaganda is slanted or incomplete information. Both sides in a conflict use propaganda to try to affect morale. Each side wants to make the other side look evil and to make its own victory seem within reach. A government wants to convince its own troops and civilians that the war is worth fighting. It will try to make the enemy doubt the value of continuing to fight.
If you want to see these terms in context, you can find much of this war vocabulary on many history or news websites. One place to start is this History.com page on D-Day. (It tells about Allied landings in the North of France in 1944. D-Day was the start of a World War II campaign to take back western Europe from Germany.)
There’s also a closely related page on EnglishHints: Vocabulary for Violence.