Shedrow
Stable area. A row of barns.  

Sheets
A handicapping tool assigning a numerical value to each race run by a horse to enable different horses running at different racetracks to be objectively compared.  

Short
A horse in need of more work or racing to reach winning form.  

Show
Third position at the finish.  

Show Bet
Wager on a horse to finish in the money; third or better.  

Shut Off
Unable to improve position due to being surrounded by other horses.  

Silks
Jacket and cap worn by riders to designate owner of the horse, or at some smaller tracks, to designate post positions (e.g., yellow for post position one, blue for two, etc.).  

Simulcast
A simultaneous live television transmission of a race to other tracks, off-track betting offices or other outlets for the purpose of wagering. 

Sire
1) The male parent. 2) To beget foals.  

Sloppy (track)
A racing strip that is saturated with water; with standing water visible.