Plain English Meaning

It's the path the airplane traces across the ground while climbing out, when the wind is blowing from the side. The pilot points the nose a little into the wind so the airplane keeps tracking straight out from the runway instead of being blown sideways.

Full Definition

The actual track an airplane follows over the ground during the initial climb after takeoff when a wind is blowing across the runway. Because the wind pushes the airplane sideways, the pilot must turn the nose slightly into the wind (crab) so that the airplane's path over the ground stays aligned with the extended centerline of the runway rather than drifting downwind.

Context Anchor

Seen during takeoff and initial climb, especially when keeping the airplane aligned with the after .