in the psychoanalytic theory of Melanie Klein, this refers to the mental representation (see introjection) of the mother’s breast as being unsatisfying. According to Klein, the infant first experiences the mother and the nourishing breast as part-objects with positive and negative qualities – the good and bad breast.
BAD BREAST: “A person with a mental representation of the bad breast, likely experienced his or her mother’s breast as unsatisfying in some manner. “