Plain English Meaning
Something that pushes or pulls on an object. The strength of the push or pull, and the direction it acts in, both matter.
Full Definition
A push or pull acting on an object, capable of changing its motion, direction, or shape. In aerodynamics, force has both magnitude (how strong it is) and direction, and is typically measured in pounds.
Context Anchor
Used when describing how an airplane moves and responds to pilot control, engine power, air moving over the wings, gravity, and braking.
Derivation
From the Latin 'fortis,' meaning 'strong.' The word originally described physical strength or power exerted on something — which carries directly into the aviation meaning of a push or pull acting on the airplane.