noun
Medical term for a congenital split in the upper lip. In everyday contexts, 口唇口蓋裂 (cleft lip and palate) or 兎唇 (rare, potentially offensive) may be encountered.
口唇裂は、胎児期に上唇が正常に形成されない先天異常です。
Cleft lip is a congenital anomaly in which the upper lip does not form properly during the fetal period.