Shield generator

From the Encyclopedia of Speculative Fiction - http://encyclopedia.wizards.pro

A shield generator is a piece of equipment which generates some type of electromagnetic or force field, designed to deflect kinetic or electromagnetic energy.

During the Second Battle of Deep Space 9, the Dominion destroyed Deep Space 9's shield generator. (DS9: "Call to Arms")

The USS Defiant (NCC-75633)'s shield generators were configured differently from its predecessor. (DS9: "The Dogs of War")

The phrase "Shields Up!" which saw widespread use in Star Trek, probably had its origin in classical warfare, when infantry would raise their shields to defend against incoming arrows or other projectiles. The order would be given when it was time for the solder to raise his shield from the carry position.