Plain English Meaning
Flying the airplane at exactly the speed you want, and keeping it there, without drifting faster or slower.
Full Definition
The skill of holding a chosen airspeed accurately and consistently during a maneuver, using coordinated pitch and power adjustments to stay within a narrow tolerance of the target value.
Context Anchor
Seen in flight training when practicing climbs, descents, approaches, landings, stalls, and other maneuvers where the instructor expects to a speed.