The ejection port in a firearm is essentially a hole, cut out of the firearm's receiver or slide, where the action can eject spent cartridge cases when it cycles. This is true for either manual action firearms such as bolt actions or for semi-automatic or fully automatic actions, either handguns or long guns. The term is fairly generic, and can be applied more broadly - for example, on aircraft which contain internal machine guns or cannons, there is usually an ejection port in the fuselage or wing (matching the one in the fun itself) where spent cases can exit the airframe.