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).
WCMD Wind-Corrected Munition Dispenser, being an add-on to the US series of CBU-78/B, CBU-87/B CEM and CBU-98/ Gator cluster munitions.
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).
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.
WVR Within Visual Range.