Plain English Meaning

The point of landing when there is a wind blowing across the runway. The pilot tilts the airplane slightly into the wind and uses the rudder to keep the nose pointed straight down the runway, so the wheel on the windward side touches down first.

Full Definition

The moment of landing in a crosswind when the airplane's main wheels first contact the runway while the pilot uses aileron into the wind and opposite rudder to keep the airplane aligned with the runway centerline and tracking straight down it. In a properly executed crosswind touchdown, the upwind main wheel contacts first, followed by the downwind main wheel, and then the nosewheel, with the of the airplane parallel to the direction of travel.