A short takeoff and landing (STOL) aircraft is a fixed-wing aircraft that can take off and land on runways that are much shorter than the typical ones needed for conventional take-off and landing. STOL-capable aircraft are usually light aircraft (mostly propeller-driven utility aircraft, sporters or motor gliders) with a high lift-to-drag ratio and typically also a high aspect ratio, allowing them to achieve minimum takeoff speed (i.e. liftoff speed or VLOF) much more quickly and thus requiring a shorter accelerating run before taking off (takeoff roll); and perform landing at a lower minimum steady flight speed (VS0) and thus also a shorter decelerating run (rollout).
Gyrocopters, despite being rotary-wing aircraft, need a forward motion to drive air flow past autorotating rotor blades to generate lift and thus still mandate runways (albeit a very short one) for takeoff and landing. They are therefore also considered STOL aircraft, as they cannot perform vertical takeoff and landing like helicopters.