Meaning “thoroughbred horse,” the term is used here and in the introductory narratives of many sūtras as a metaphor for nobility.

When used to describe the mind, the thoroughbred horse is used as metaphor for the nobility, speed, strength, and refinement of intelligence.

Being the best of a particular kind, a combination of good breeding and good training, a term that is applied to animals as well as humans, and perhaps particularly of horses in the sense of a thoroughbred.