1.NounThe dirt or other material on the edge of a baseball or softball field that warns a player that he or she is approaching the fence, especially the portion in the outfield.
"Fly ball to deep center. Shelby goes back and makes the catch on the warning track."
2.NounA non-racing surface at the margin of a racing course, representing the edge of the race track.
3.NounA non-driving surface at the edge of a road, with a different surfacing warning drivers of the approach to the edge of the road, as part of the shoulder of a road.