A b**ch is a female dog, according to the dictionary. The dam is the mom and the sire is the dad, just like with horses. So, as an example, if I bred Dawn and Phantom and got pups, Dawn would be the dam and Phantom the sire. But as of right now, I have no intention of breeding, my dogs are too young and haven't had their health screens yet. So Dawn is a b**ch, and Phantom is still a pup under 1 year of age. And when Phantom does get old enough to breed I can refer to him as a stud.
Now, some people, including me, will only call an intact female a b**ch. So even though b**ch can be used to refer to any female dog, it is now commonly used to refer to intact females capable of producing a littler. Some people think that b**ch only refers to the female when in heat. So, like many words the meaning has been changed by usage. Most teenagers think b**ch is only a insult and have no clue it is an actual term applied to an animal. And there is the fact that because of our new political correctness, strict laws, and crazy animal rights groups saying the word often gets you angry glares and words from parents. So the term b**ch has fallen slightly out of use, in an attempt to avoid causing scenes and making waves with bad public opnion. Breeder will use the term among other breeders, but not in public.
Idiot animal rights groups are so anti-breeder that they make life very difficult once they set their sights on a particular breeder. PETA being 1 of the worst. If PETA had its way, ALL dogs would be spayed or neutered and then we would have no more pet dogs. So many good breeders do their best to stay off the radar, and keeping some kids mommy and daddy from complaining about foul language is a tiny price to pay.