Definition
The tendency of an airplane's nose to yaw in the opposite direction of a roll when the ailerons are deflected. The down-going aileron (on the rising wing) creates more lift but also more induced drag than the up-going aileron on the descending wing, pulling that wing back and yawing the nose away from the intended turn.
Plain English
When you roll the airplane into a turn using the ailerons alone, the nose initially swings the wrong way — away from the turn — before coming around. The wing that goes up creates extra drag, which drags that side of the airplane backward.
Context Anchor
You encounter adverse yaw during basic flight training when learning turns, roll control, and proper rudder use.
Derivation
Adverse' comes from the Latin 'adversus,' meaning 'turned against' or 'opposed.' 'Yaw' is the rotation of the aircraft's nose left or right around its vertical axis. Together: a yaw that works against what the pilot is trying to do.
Why Pilots Care
Uncorrected adverse yaw produces uncoordinated flight, sideslip, and increased drag that can affect turn performance and stall margins.
Grounding Statement
Picture beginning a left turn and, for a moment, the airplane's nose tries to swing right before the turn settles in.
Intuition Check
Do not assume the airplane's nose automatically points into the turn as soon as you move the control wheel or stick. With adverse yaw, the roll starts one way while the nose tends to swing the opposite way.
Example Sentence 1
The instructor demonstrated adverse yaw by rolling into a left bank using only the ailerons, and the nose visibly swung to the right before the turn began.
Example Sentence 2
The pilot used coordinated rudder to cancel adverse yaw and keep the ball centered during the roll.