Foal(ed)
1) A horse of either sex in its first year of life. 2) As a verb, to give birth. Also known as "dropped." 3) Can also denote the offspring of either a male or female parent -- She is the last foal of Secretariat.  

Founding Sires
The Darley Arabian, Byerly Turk and Godolphin Barb. Every Thoroughbred must be able to trace its parentage to one of the three founding sires.  

Fractional Time
Intermediate times recorded in a race, as at the quarter, half, three-quarters, etc. The "quarter time," for example, refers to the time after the first quarter-mile, not the first 25 percent of the race.  

Front Runner
A horse whose running style is to attempt to get on or near the lead at the start of the race and to continue there as long as possible. 

Full Sibling
Horses that share the same sire and dam.  

Furlong
One-eighth of a mile, 220 yards, 660 feet.  

Futurity
A race for two-year-olds in which the owners make a continuous series of payments over a period of time to keep their horses eligible.