A charger is the accessory you plug into your phone or laptop when the battery power is low. If you're bringing your digital camera with you on vacation, it's important to remember your charger.
Devices that are powered by rechargeable or internal batteries need a charger to keep that battery working. When you plug a laptop charger into an outlet, a jolt of electricity recharges the laptop battery's cells. An entirely different kind of charger is a war horse — a large, sturdy animal that was trained to carry soldiers in battle. This is the 18th century meaning of charger, and it's based on the verb charge and its meaning "rush into battle."