Airspeed is how fast a plane is moving through the air around it. That is what the wings feel, and it is what pilots watch, because a wing needs a certain rush of air to keep the plane up. Though actually, that is not always the same as how fast the plane is crossing the ground. A tailwind can carry you over the land quickly while the airspeed stays moderate; a headwind can make you crawl over the map while the airspeed is high. Everyday speakers sometimes just mean “how fast the plane is going,” which is the tidy dictionary line — but that mixes airspeed with ground speed. This is an aviation word. Passengers usually ask “how fast are we flying?”; the cockpit talks airspeed.