- washout Inbuilt twist of wing or rotor blade reducing angle of incidence towards the tip.
- watt SI unit of power, equal to 1 Js-1 (one Joule per second).
- WDNS Weapon delivery and navigation system.
- wet Housing fuel; wet wing often has extra connotation of integral tankage. Wet pylon can accommodate external fuel tank.
- wheelbase Minimum distance from nosewheel or tailwheel (centre of contact area) to line joining mainwheels (centres of contact areas).
- wide-body Passenger aircraft with cabin wide enough to have two longitudinal aisles between seats.
- wing area Total projected area of clean wing (no projecting flaps, slats and so on) including all control surfaces and area of fuselage bounded by leading- and trailing-edges projected to centreline (inapplicable to slender-delta aircraft with extremely large leading-edge sweep angle). Described in Jane's as gross wing area; net area excludes projected areas of fuselage, nacelles, and so on.
- wing loading Aircraft weight (usually MTOW) divided by wing area.
- winglet Small auxiliary aerofoil, usually sharply upturned and often sweptback, at tip of wing.
- WSO Weapon(s) system(s) officer.
