Apprentice

A new jockey who has not ridden a certain number of winners in a specified time period.

Bobble/Stumble

A slip or a duck from a horse trying to leave the starting gates, often caused by the surface giving way under the feet. This can range from a mild misstep to a stumble down to their knees.

Fractions

The times recorded during the race; with timing starting just past the gate or when the gates open, then parroted for the quarter, half, three-quarters etc. Used as an indication of ability and speed.