Wingtip device

A structure attached to an aircraft wingtip that changes airflow around the wing. It is designed chiefly to reduce induced drag or improve aerodynamic efficiency.

Wingtip vortex: A rotating airflow structure that trails from a wingtip as air moves from the high-pressure lower surface toward the low-pressure upper surface. Wingtip devices reshape or weaken these vortices to reduce the drag they cause.
Lift: The aerodynamic force perpendicular to a body's motion through a fluid, generated by pressure differences and airflow deflection. A wingtip device modifies the flow associated with producing lift.
Blended winglet: A smoothly curved wingtip extension that joins the wing to an upward-curving surface with minimal angular discontinuity. It is a widely used commercial-aircraft design for reducing cruise drag.
Wingtip fence: A pair of small vertical surfaces extending above and below a wingtip to manage spanwise airflow. Its compact paired surfaces contrast with larger upward winglets and raked tips.
Aircraft fuel efficiency: The amount of useful flight or transport produced per unit of fuel consumed by an aircraft. Lower aerodynamic drag can reduce cruise fuel consumption on suitable aircraft.
Induced drag: The drag component associated with generating lift, arising from airflow patterns around a finite wing. Reducing induced drag is the primary aerodynamic aim of many wingtip devices.
Finite-wing theory: Aerodynamic theory describing how a wing of limited span generates lift and drag, including spanwise flow and wingtip vortices. Wingtip devices address aerodynamic effects that arise because real wings have finite span.
Sharklet: Airbus's trademarked upward-curving wingtip device used on several airliner families. It is a prominent commercial implementation of a wingtip device.
Winglet: An upward-curving or angled surface at a wingtip designed to reduce induced drag. It is one specific, familiar form within the broader class of wingtip devices.
Wing bending moment: The internal turning effect produced by loads acting along an aircraft wing, especially lift and weight. Increasing effective span can raise structural loads that designers must accommodate.

Linked from 1 page

Airbus A350Related: The A350’s curved wingtip geometry helps reduce induced drag.