Plain English Meaning
A practice exercise where the pilot flies the airplane as slowly as it can be flown without stalling, holding altitude and heading steady while learning how the controls feel at very low speed.
Full Definition
A training maneuver in which the airplane is flown at an airspeed just above the stall, where any further reduction in airspeed, increase in load factor, or addition of power will result in an immediate stall warning. The pilot maintains altitude, heading, and coordination while the airplane is operating in the , where more power is required to fly slower.