noun. An irregular amplification of the skeletal appendages, such as legs and arms, and areas of the cranium. The illness is not common and is generally seen in adults with normal skeletal development that has ceased. The illness is elicited by a pituitary-gland irregularity that alters and increases the amount of growth hormone secreted into the body. In kids who are still developing, the result is known as gigantism.
ACROMEGALY: "Acromegaly is similar to gigantism, but exists in mature adults."