- Black type
- Bold type in a catalogue marking a horse that won (capitals) or was placed (lower case) in a Listed or Group/Graded race. The standard measure of class.
- Group and Graded races
- The top level of flat racing: Group 1, 2 and 3 in Europe (Grade 1, 2 and 3 in America). Group 1 is the highest.
- Listed race
- The level just below Group 3. A Listed win or place also earns black type.
- Classics
- The five historic races for three-year-olds: the 2,000 and 1,000 Guineas, the Derby, the Oaks and the St Leger, with their Irish and French equivalents.
- Sire and dam
- The father and the mother.
- Damsire (broodmare sire)
- The dam's sire: the horse's maternal grandfather.
- Second dam, third dam
- The dam's mother, and her mother. Catalogues list their best produce too.
- Produce
- A mare's foals. The produce record lists each one and what it achieved.
- Half-brother, half-sister
- In racing, horses out of the same dam by a different sire. Horses by the same sire are not usually called siblings.
- Full brother, full sister
- Same sire and same dam.
- Chef-de-race
- A stallion on the dosage list of influential sires, placed in one or two aptitude groups from Brilliant (speed) to Professional (stamina).
- Dosage Profile (DP)
- Five numbers, B-I-C-S-P, totalling the points from chefs-de-race in the first four generations.
- Dosage Index (DI)
- Speed points divided by stamina points from the Dosage Profile. Around 1 is balanced; higher leans to speed.
- Centre of Distribution (CD)
- The Dosage Profile's balance point, from +2 (all speed) to −2 (all stamina).
- Family number
- The number of the foundation mare at the bottom of the female line, from Bruce Lowe's system, with a letter for the sub-family (e.g. 13-e).
- HorseBytes family line (HB code)
- A horse’s female line traced to the earliest mare in the HorseBytes database, its founder. Written HB 12 for the family and HB 12-c for one branch. See HorseBytes family lines.
- Founder
- The earliest mare of a HorseBytes family line. Every mare descended from her through her daughters belongs to her family.
- Branch
- One daughter of a family’s founder and everything descended from her: the letter in HB 12-c.
- Family line rating
- A 0–100 score of how strong a HorseBytes family line is against every other family, from its black-type winners, Group 1 winners and recent winners.
- HorseBytes Index
- A 0–100 rating of a young horse’s pedigree from the HorseBytes System: the sire’s black-type winners, the dam’s age, and the black-type winners of the dam, 2nd and 3rd dams and the dam’s sire, each weighted by how much it has mattered. 80 means a stronger pedigree than 80% of young horses. See the HorseBytes System.
- Back-test
- Checking a rating on horses whose careers are already known: give each one the rating it would have had when it was sold, then see how the ratings compare with what the horses went on to do.
- Conduit mare
- A mare who was no star herself but passed her family's quality on to her foals.
- Inbreeding (e.g. 3x4)
- The same ancestor appearing twice in a pedigree. 3x4 means in the third generation on one side and the fourth on the other.
- Nick
- A sire line and damsire line said to combine well. Worth treating with caution: many nicks rest on small numbers.
- Strike rate
- The share of runners that won. For a broodmare, her winners divided by her runners.
- Furlong (f)
- An eighth of a mile, about 201 metres. A mile is 8f; 1m2f is 10f.
- Vendor and consignor
- The vendor owns the horse being sold; the consignor prepares and presents it at the sale, often for the vendor.
- Breeze-up
- A sale of two-year-olds who gallop (breeze) in front of buyers a few days before the auction.
- Horses in training (HIT)
- A sale of horses already racing or in a trainer's yard, often with form of their own.
- Store
- A young jumps-bred horse sold unbroken or lightly handled, to be brought on for National Hunt racing.