ejector

noun

1. a person or thing that ejects.
2. (in a firearm or gun) the mechanism that after firing throws out the empty cartridge or shell.
3. Also called eductor. a device for inducing a flow of a fluid from a chamber or vessel by using the pressure of a jet of water, air, steam, etc., to create a partial vacuum in such a way as to entrain the fluid to be removed.
4. any of various devices for removing work from a machine or die.

noun

1. a person or thing that ejects
2. the mechanism in a firearm that ejects the empty cartridge or shell after firing