​MONGREL (earliest form mengrel, probably from the root meng-, or mong-, to mix, cf. mingle, among), a dog that is the progeny of two different breeds, or one whose breed it is impossible to tell on account of the various crossings. In the case of other animals or plants it is the result of a fertile cross between two varieties of the same species, and so to be distinguished from a “ hybrid,” the result of a fertile cross between two distinct species (see Hybridism).