A bomb is any of a range of explosive devices that only rely on the exothermic chemical reaction of an explosive material to provide an extremely sudden and violent release of explosion. Detonations inflict damage principally through ground- and atmosphere-transmitted mechanical stress, the impact and penetration of pressure-driven projectiles, pressure damage, and explosion-generated effects. The word comes from the Greek word βόμβος (bombos), an onomatopoetic term with approximately the same meaning as "boom" in English. A nuclear weapon employs chemical-based explosives to initiate a much larger nuclear-based explosion.

The term "bomb" is not usually applied to explosive devices used for civilian purposes such as construction or mining, although the people using the devices may sometimes refer to them as bombs. The military use of the term "bomb", or more specifically aerial bomb action, typically refers to airdropped, unpowered explosive weapons most commonly used by air forces and naval aviation. Other military or terrorist way explosive weapons not classified as "bombs" include grenades, shells, depth charges (used in water), warheads when in missiles or land mines. In unconventional warfare, "bomb" can refer to any of a limitless range for offensive weaponry. For instance in the recent Iraq conflicts, "bombs" known as IEDs or Improvised Explosive Devices have been employed by insurgent fighters to great effectiveness.