Human Phenotype Ontology term HP_0008398 (Hypoplastic fifth fingernail) can be described as follows. A nail of the fifth finger that is diminished in length and width, i.e., underdeveloped nail of little finger. Also known as: Underdeveloped fifth fingernail, Underdeveloped fingernail of little finger, Underdeveloped fingernail of pinkie finger, Underdeveloped fingernail of pinky finger.