Cleft lip and cleft palate, which can also occur together as cleft lip and palate are variations of a type of clefting congenital deformity caused by abnormal facial development during gestation. This type of deformity is sometimes referred to as a cleft. A cleft is a sub-division in the body’s natural structure, regularly formed before birth. A cleft lip or palate can be successfully treated with surgery soon after birth. Cleft lips or palates occur in somewhere between one in 600-800 births.

The term hare lip is sometimes used colloquially to describe the condition because of the resemblance of a hare’s lip. The Chinese word for cleft lip is tuchun (兔唇), literally “harelip.”