In the most literal sense a bitch is a female canine, but in modern language this term is often used in a derogatory way to refer to an individual. While the word bitch is typically used to refer to females sometimes it is used for men as well, and it is meant as a put down. When a man is called a bitch this basically means that they are acting like a woman, and when the word refers to a female it means that she is not living up to the expectations for this gender.