A specific type of val which defines an equal-temperament, which is a closed tuning system.
The name was coined by Paul Erlich -- primarily to refer to the process of "breeding" different ET species together (each represented by a breed, because it is one) to create "cross-breeds", which are the multidimensional tuning systems like meantone, and secondarily to honor the work of Graham Breed, who initiated computer algorithms which calculate tunings in this way.
A breed is exactly the "dual" of a Monzo. It's firstly a prime-mapping covector, representing an equal temperament of some Just Intonation tuning/lattice by giving the list of numbers of steps required to reach each prime; e.g. <12 19 28] for the usual 12-equal breed. Which is a second meaning -- the equal temperament itself regardless of whether or not the list of prime mappings is explicit. I followed Gene's example. Another 12-equal breed is represented <12 19 27] (the mapping covector), or 12c (wart notation). 12 and 12c are different breeds of 12EDO, and are different equal temperaments in the sense that they temper different commas ("monzos" whose JI cents, divided by harmonic distance, is usually small) out from 5-limit JI -- they temper JI differently. But they can both be tuned to 12-EDO, which is itself agnostic as to any JI derivation.
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