A two-year-old horse. Every horse officially turns two on January 1, at the start of the second full calendar year following its birth e.g. a horse born in 2010 will turn two on January 1, 2012.
- Juvenile hurdler
The youngest category of hurdler – juvenile hurdlers are those that turn four years of age (on January 1) during the season in which they start hurdling.
The Jackpot is a tote bet that requires the selection of the winners of the first six races at a selected meeting. The minimum bet is 50p
- Jocked off
Term used to refer to when one jockey is replaced by another on a horse he usually rides or for which he has already been booked to ride in a particular race.
If two horses have the shortest odds in the betting, they are described as joint-favourites; if three or more horses have the shortest odds, they are co-favourites.
Racecourse official responsible for declaring the finishing order of a race and the distances between the runners.