Plain English Meaning
A way of flying on instruments where you first set the airplane's nose position and engine power to what should produce the flight you want, then you check the other instruments to see if it actually worked, and adjust if it didn't.
Full Definition
A method of attitude instrument flying in which the pilot establishes a desired aircraft attitude and power setting using the control instruments (attitude indicator and power indicators), then cross-checks the performance instruments (altimeter, airspeed indicator, vertical speed indicator, heading indicator, and ) to confirm the is achieving the , making small corrections to or as needed.