1 : a great change in appearance or character. 2 : the process of great and usually rather sudden change in the form and habits of some animals during transformation from an immature stage (as a caterpillar) to an adult stage (as a butterfly) metamorphosis. noun. meta·​mor·​pho·​sis | ˌmet-ə-ˈmȯr-fə-səs WhereRead More →