outbreed

To outbreed most often means to breed animals or plants with individuals from a different breed, strain, or family line instead of breeding within a very narrow line. In that sense, it is the opposite of inbreed. The idea is to bring in new genetic material, which can help improve health, hardiness, fertility, and general adaptability. Farmers, breeders, and conservation workers may do this to reduce the problems that can build up when closely related individuals keep breeding with each other.

The word can also mean to reproduce more successfully than another group. In population or evolutionary discussion, one group may outbreed another simply by producing more offspring over time. In that case, the focus is not on mixing bloodlines but on greater reproductive success.

So when you meet this word, it usually points to one of two ideas: breeding outside a close family line, or having more offspring than a rival group. The first use is common in agriculture, animal breeding, plant breeding, and conservation. The second appears more in biology, demography, and discussions of population change.