This term is most commonly used in the context of animals, but can also be applied to plants.
Here are some examples:
* Dogs: A hunting dog is purpose-bred for its ability to track, flush, and retrieve game.
* Horses: A racehorse is purpose-bred for its speed and endurance.
* Cattle: A dairy cow is purpose-bred for its high milk production.
* Plants: A tomato variety is purpose-bred for its flavor, size, or yield.
Essentially, "purpose-bred" implies that these organisms have been selectively bred over generations to enhance certain traits that make them suitable for a specific function.