An abnormality of the premaxilla (the embryonic structure that forms the anterior part of the maxilla) causing it to appear relatively small in size compared to the other parts of the maxilla or other facial structures. The phenotype is Hypoplasia of the premaxilla (HP_0010650, a Human Phenotype Ontology entry). Also known as: Decreased size of premaxilla, Decreased size of the primary palate bone, Hypoplasia of the intermaxillary bone, Hypoplasia of the primary palate bone, Premaxillary bone deficiency, Premaxillary underdevelopment, Primary palate bone deficiency, Small premaxilla.