pazyprasi'u lujvo

x1 (set) is composed of members which interbreed with one another.

This statement does not merely say that they *can* mutually interbreed, but that they *do*. It is uncertain whether it would be acceptable to use this word in reference to a set of cardinality greater than two in binary-sexed sexual species (for example: a set of two women and one man may be said to internally interbreed if the man breeds with each woman, but the women would be incapable of breeding with one another).