Congenital malformation consisting of one or more clefts in the upper lip, the result of failed closure in the embryo of the maxillary and median nasal processes.
See also: cleft palate
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 737 (https://doi.org/10.1515/pac-2015-1202)