Plain English Meaning
When something moves in a circle or curve, there has to be a force pulling it toward the middle of that curve. That inward pull is centripetal force.
Full Definition
The inward force that acts on an object moving along a curved path, pulling it toward the center of the curve and keeping it on that curved path rather than continuing in a straight line.
Context Anchor
Seen in discussions of aircraft turns, propellers, wheels, and other rotating aircraft parts.
Derivation
From Latin 'centrum' (center) and 'petere' (to seek). Literally 'center-seeking.' That captures the idea exactly: a force that pulls the object toward the center of its circular path.
Why Pilots Care
In a banked turn the horizontal component of lift supplies this force; insufficient centripetal force causes the airplane to skid outward.