Step Up
A horse moving up in class to meet better competition.  

Steward
Officials of the race meeting responsible for enforcing the rules of racing.  

Stretch
Final straight portion of the racetrack to the finish.  

Stretch Call
Position of horses at the eighth pole.  

Stretch Runner
Horse that runs its fastest nearing the finish of a race.  

Stride
Manner of going. Also, distance covered between successive imprints of the same hoof.  

Stud
1) Male horse used for breeding. 2) A breeding farm.