Fig. an unpleasant fact that has to be accepted. (Does not involve pills or swallowing.) It was a bitter pill for her brother to swallow when she married his enemy.We found his deception a bitter pill to swallow.
An unpleasant fact, disappointment, or humiliation that is difficult to endure. For example, Failing the bar exam was a bitter pill to swallow, but he plans to try again next year . [Late 1500s]