Pump Action
A manually-operated action cycled by sliding a forend back and forth.
Also: slide action
A pump-action shotgun or rifle is cycled by the support hand pulling the forend rearward (ejecting the spent shell) and pushing it forward (chambering a new round). Pump shotguns are the workhorse defensive and hunting shotgun in the US — extremely reliable, ammo-tolerant, and inexpensive.