gigantism

noun
  1. 1

    The quality or state of being gigantic; being of abnormally large size.

  2. 2

    A condition where there is over-production of growth hormone by the pituitary gland in a child before the bone growth plates close, resulting in excessive long bone growth, accompanied by muscular weakness and sexual impotence.

Source: https://en.wiktionary.org/wiki/gigantism