Plain English Meaning

Pushing the control wheel or stick the other way from the direction the airplane is rolling, to stop it from rolling further. If the airplane is banking left and wants to keep banking more steeply, you apply right aileron pressure to hold the bank where you want it.

Full Definition

Aileron input applied in the direction opposite to the airplane's bank or roll tendency, used to control or counteract an unwanted rolling motion. In maneuvers such as the lazy eight, opposite aileron pressure is progressively applied as the airplane reaches steep bank angles and slow airspeeds to prevent the bank from increasing further due to the overbanking tendency.