Plain English Meaning
How high the airplane's nose is held above the horizon to make the airplane climb steadily at the right speed.
Full Definition
The pitch position of the airplane, relative to the horizon, that produces a sustained climb at the desired airspeed and power setting. It is the nose-up attitude the pilot establishes and holds on the attitude indicator and outside horizon during the climb.
Context Anchor
Used when establishing a climb, especially after takeoff, during a go-around, or any time the pilot changes from level flight to climbing flight.