Dwarfism is a condition wherein an organism is exceptionally small, and mostly occurs in the animal kingdom. In humans, it is sometimes defined as an adult height of less than 147 centimetres (4 ft 10 in), regardless of sex; the average adult height among people with dwarfism is 122 centimetres (4 ft 0 in). Disproportionate dwarfism is characterized by either short limbs or a short torso. In cases of proportionate dwarfism, both the limbs and torso are unusually small. Intelligence is usually normal, and most have a nearly normal life expectancy. People with dwarfism can usually bear children, though there are additional risks to the mother and child dependent upon the underlying condition.

The most common and recognisable form of dwarfism in humans (comprising 70% of cases) is achondroplasia, a genetic disorder whereby the limbs are diminutive. Growth hormone deficiency is responsible for most other cases. Treatment depends on the underlying cause. Those with genetic disorders can sometimes be treated with surgery or physical therapy. Hormone disorders can also be treated with growth hormone therapy before the child's growth plates fuse. Individual accommodations, such as specialized furniture, are often used by people with dwarfism. Many support groups provide services to aid individuals and the discrimination they may face.

In addition to the medical aspect of the condition, there are also social aspects. For a person with dwarfism, height discrimination can lead to ridicule in childhood and discrimination in adulthood. In the United Kingdom, United States, Canada, Australia, and other English-speaking countries, labels that some people with dwarfism accept include dwarf (plural: dwarfs), little person (LP), or person of short stature (see Terminology). Historically, the term midget was used to describe dwarfs (primarily proportionate); however, some now consider this term offensive.