What is lift on a wing most properly defined as?

Lift on a wing is most accurately characterized as a force acting perpendicular to the relative wind. This definition emphasizes the fundamental aerodynamic principle that lift opposes the weight of the aircraft and acts in a vertical direction when considering the aircraft's orientation in flight. The interaction between the airflow and the wing shape, known as the airfoil, causes variations in pressure over and under the wing, resulting in the creation of lift.

While other choices introduce relevant concepts related to the mechanics of lift, they do not capture the essence of the term "lift" as succinctly or accurately as saying it is a force acting perpendicular to the relative wind. This choice highlights the relationship between the aerodynamic forces and the direction of flow, which is essential for understanding how lift is generated as an aircraft moves through the air.

In aerodynamic practice, comprehending that lift is a force at an angle to the relative wind helps in visualizing how aircraft maneuver and how various factors, like angle of attack, can influence this lift force.