Dwarfism refers to a condition of extreme small size of an animal, or plant. Any type of marked human smallness could be termed dwarfism in older popular and medical usage. The term as related to human beings (the major subject of this article) is often used to refer specifically to those forms of extreme shortness characterized by disproportion of body parts, typically due to an inheritable disorder in bone or cartilage development.
Forms of extreme shortness characterized by proportional body parts usually have a hormonal or nutritional cause. An example is growth hormone deficiency, once known as "pituitary dwarfism".
The Little People of America (LPA) defines dwarfism as a medical or genetic condition that usually results in an adult height of 4'10" (147 cm) or shorter.
