"Hare lip" is an outdated term that is considered insensitive or derogatory by some people. The more appropriate and commonly used term is "cleft lip." This condition occurs when the upper lip does not form properly during fetal development, resulting in a split or gap in the lip. Some synonyms that can be used instead of "hare lip" include "split lip," "cleft lip and palate," "lip fissure," and "labial cleft." It is important to use respectful and appropriate language when discussing medical conditions in order to avoid causing offense or perpetuating prejudice.