ejection

Ejection is the act of forcing something out of a container, system, or body, or the result of that action. It is used across many fields to describe the sudden expulsion of matter or energy, often driven by pressure, mechanical action, or internal forces. The word derives from Latin eicere, to throw out.

In mechanical and everyday contexts, ejection describes items being expelled from devices. Examples include cartridge cases ejected from firearms after firing, or products and consumables expelled from printers or machines. Ejector mechanisms typically use springs, pneumatics, or gas pressure to clear a chamber.

In aviation and spaceflight, an ejection system enables a pilot or crew member to escape an aircraft or spacecraft in an emergency. Ejection seats deploy parachutes and decouple the occupant from the vehicle. The concept also appears in space contexts, where propulsion systems or debris are expelled from spacecraft during operations.

In volcanology and geology, ejecta are materials expelled during eruptions, such as ash clouds, pumice, and volcanic bombs.

In biology and botany, ejection describes active dispersal or expulsion of material, such as seeds or spores released by mechanical means, or venom or other substances expelled as a defense.

In astronomy and astrophysics, ejection describes the removal of matter from a system, such as jets of gas emitted by young stars or active galactic nuclei, or stars accelerated to escape velocity in gravitational interactions.

Ejection is thus a general term spanning many disciplines, referring to the act or product of pushing or throwing something outward.