stall speed

Etymology
From how attempting to slow below this speed by pulling back on the nose will cause the aircraft to stall.

Noun

 * 1)  The airspeed at which the lift generated by an aircraft flying with an angle of attack equal to the stall angle (the point of maximum lift for a given airspeed) is exactly equal to the aircraft's weight; the minimum airspeed at which it is possible to maintain level unaccelerated flight.