Plain English Meaning
How many times heavier than normal the airplane and the people inside it feel during a maneuver. At 1 G everything weighs its usual amount. At 2 G everything feels twice as heavy.
Full Definition
The load imposed on an airplane and its occupants expressed as a multiple of the force of gravity. A G load of 1 equals normal weight in level flight; a G load of 2 means the airplane and everything in it momentarily weigh twice their normal amount, typically produced by maneuvering, turbulence, or abrupt control inputs.
Context Anchor
Encountered when studying steep turns, pull-ups, accelerated stalls, and aircraft operating limits.