Midget is a term used to describe an exceptionally short person. The terms "midget" and "dwarf" are often used synonymously, as both terms mean someone who has been short in stature since birth, but those terms were not originally synonyms.
Midget is a term that was originally coined in 1865, referring to an extremely short but normally proportioned person. P.T. Barnum indirectly helped popularize "midget" when he began featuring General Tom Thumb in his circus. Dwarf was originally used to denote those with short limbs as compared to those who had proportioned limbs. Like many other older terms, "midget" has became part of popular language, it was often used in a pejorative sense. When applied to a person who is very short, midget is now often considered offensive, an example of the euphemism treadmill.
Unusual shortness of stature is caused by an inherited gene and can be diagnosed at birth by several telltale signs or later when the child is a toddler. The word dwarf has generally replaced midget though the term little person is preferred. According to the Little People of America, dwarfism is "a medical or genetic condition that usually results in an adult height of 4 [feet] 10 [inches] [(147 cm)] or shorter, among both men and women, although in some cases a person with a dwarfing condition may be slightly taller than that.
Modern terminology now distinguishes between the two types of dwarfism using the terms proportionate dwarfism, such as primordial dwarfism, and disproportionate dwarfism, such as achondroplasia. Proportionate dwarfism is often the result of a hormonal deficiency (such as growth hormone deficiency), and it may be treated medically.
Webster's New Collegiate Dictionary (Merriam-Webster, 1961) defines "midget" in the noun form as "a very diminutive person", and in the adjective form as "like a midget in size; very diminutive", hence its usage as a synonym for "miniature", as with cars.