Nuclear Weapons Glossary
50 defined terms covering nuclear weapon effects, physics, doctrine, and arms control. Each term has a one-sentence answer suitable for citation, plus a deeper explanation.
Nuclear weapon effects
Acute Radiation Syndrome
The constellation of medical symptoms following a high dose of ionizing radiation, including nausea, immune-system failure, hemorrhage, and death.
Air Burst
A nuclear detonation above the ground at optimal altitude, maximizing the area affected by blast and thermal radiation while producing minimal fallout.
EMP (Electromagnetic Pulse)
A burst of electromagnetic energy released by a nuclear detonation, capable of damaging or destroying unhardened electronics over a wide area.
Fallout
Radioactive material thrown into the atmosphere by a surface-burst nuclear detonation, which then settles back to earth over hours to weeks.
Fireball
The sphere of plasma created by a nuclear detonation, with internal temperatures exceeding 10 million °C — hotter than the surface of the Sun.
Nuclear Winter
A hypothesized severe global cooling caused by soot from urban firestorms following a large-scale nuclear war.
Overpressure
The pressure above atmospheric pressure produced by the blast wave of a nuclear detonation, measured in pounds per square inch (PSI).
PSI (Pounds per Square Inch)
The unit used to measure blast overpressure from a nuclear detonation.
Surface Burst
A nuclear detonation at ground level, producing roughly 40-50% smaller blast radius than an air burst but creating massive radioactive fallout.
Thermal Radiation
The intense pulse of light and infrared radiation emitted by the fireball of a nuclear detonation, capable of causing burns and igniting fires at long distances.
Weapons & delivery systems
Atomic Bomb
A nuclear weapon whose energy comes from nuclear fission of uranium-235 or plutonium-239.
Cruise Missile
A self-propelled jet- or rocket-powered missile that flies a low, terrain-following trajectory to a target.
Hydrogen Bomb
A nuclear weapon that derives most of its energy from nuclear fusion of hydrogen isotopes, ignited by a fission primary stage.
ICBM (Intercontinental Ballistic Missile)
A long-range ballistic missile (range > 5,500 km) designed to deliver nuclear warheads between continents.
MIRV
Multiple Independently-targetable Reentry Vehicle — a single missile carrying several warheads, each able to strike a different target.
Neutron Bomb
A small thermonuclear weapon designed to maximize neutron radiation output relative to blast and thermal effects.
SLBM (Submarine-Launched Ballistic Missile)
A ballistic missile launched from a submerged submarine, providing a survivable second-strike nuclear capability.
Strategic Nuclear Weapon
A nuclear weapon designed for long-range strikes against an adversary's population centers, industrial base, or strategic infrastructure.
Tactical Nuclear Weapon
A nuclear weapon designed for battlefield use, typically with low yield (sub-kiloton to ~50 kilotons) and short range.
Teller-Ulam Design
The two-stage design used in nearly all modern thermonuclear weapons, named after physicists Edward Teller and Stanislaw Ulam.
Thermonuclear Weapon
Synonym for hydrogen bomb — a nuclear weapon whose primary energy comes from fusion reactions.
Warhead
The explosive payload of a missile, bomb, or other weapon system; for nuclear weapons, the package containing the fissile or fusion material.
Nuclear physics
Boosted Fission
A fission weapon design in which a small amount of deuterium-tritium gas is injected into the fissile core to enhance yield.
Critical Mass
The minimum amount of fissile material required to sustain a self-propagating nuclear chain reaction.
Deuterium
A heavy isotope of hydrogen with one neutron, used as fusion fuel in thermonuclear weapons.
Gamma Radiation
High-energy electromagnetic radiation emitted by nuclear processes, capable of penetrating most materials and damaging living tissue.
Half-Life
The time required for half of a quantity of a radioactive isotope to decay.
Kiloton (kt)
A unit of nuclear yield equal to 1,000 tons of TNT equivalent (4.184 × 10¹² joules).
Megaton (Mt)
A unit of nuclear yield equal to 1,000,000 tons (or 1,000 kilotons) of TNT equivalent.
Nuclear Fission
The splitting of heavy atomic nuclei (typically uranium-235 or plutonium-239) into lighter fragments, releasing large amounts of energy.
Nuclear Fusion
The combination of light atomic nuclei (typically deuterium and tritium) into heavier nuclei, releasing energy.
Plutonium-239
A fissile isotope of plutonium produced from uranium-238 in nuclear reactors and used in most modern fission weapons.
Second-Degree Burns
Partial-thickness burns affecting both the epidermis and dermis, characterized by blistering and pain.
Sievert (Sv)
The SI unit of equivalent dose of ionizing radiation, accounting for biological effect.
Tritium
A radioactive heavy isotope of hydrogen with two neutrons, used as fusion fuel and in boosted-fission weapons.
Uranium-235
A fissile isotope of uranium that constitutes the explosive material in many fission weapons.
Yield
The total energy released by a nuclear weapon, expressed in tons (or kilotons / megatons) of TNT equivalent.
Doctrine & strategy
Counterforce
A nuclear targeting strategy aimed at destroying an opponent's military forces, especially their nuclear weapons and command-and-control.
Countervalue
A nuclear targeting strategy aimed at destroying an opponent's population centers, industry, and economic infrastructure.
Dead Hand
A semi-automated Soviet (and reportedly current Russian) nuclear-retaliation system that can launch a counterstrike even if national leadership has been killed.
First Strike
A nuclear attack intended to disarm an opponent before they can retaliate, by destroying their nuclear forces, command, and control.
MAD (Mutually Assured Destruction)
A Cold War strategic doctrine in which two or more nuclear-armed adversaries each possess sufficient retaliatory capability that any nuclear attack would result in their own destruction.
Nuclear Deterrence
The strategy of preventing adversary action by maintaining a credible threat of unacceptable nuclear retaliation.
Nuclear Triad
A three-pronged nuclear force structure consisting of land-based ICBMs, submarine-launched ballistic missiles (SLBMs), and strategic bombers.
Permissive Action Link (PAL)
A security device built into nuclear weapons that prevents unauthorized arming or detonation without the correct code.
Second Strike
The retaliatory nuclear capability remaining after absorbing an opponent's first strike — the foundation of deterrence under MAD.
Treaties & arms control
CTBT (Comprehensive Test Ban Treaty)
A 1996 treaty banning all nuclear explosions in all environments, for both military and civilian purposes.
New START
A 2010 US–Russia treaty limiting each side to 1,550 deployed strategic nuclear warheads and 700 deployed delivery systems.
NPT (Non-Proliferation Treaty)
The 1968 Treaty on the Non-Proliferation of Nuclear Weapons, which restricts nuclear-weapon possession to five recognized states and obligates them to pursue disarmament.
TPNW (Treaty on the Prohibition of Nuclear Weapons)
A 2017 UN treaty that prohibits all activities related to nuclear weapons — development, possession, testing, threats of use — for state parties.