La·marck·ism 
(lə-märkĭz′əm) also La·marck·i·an·ism (-kē-ə-nĭz′əm)
(lə-märkĭz′əm) also La·marck·i·an·ism (-kē-ə-nĭz′əm)n.
A theory of biological evolution holding that the changes occurring in an organism through use and disuse of its body parts in response to environmental change are inherited by its offspring.
[After Chevalier Jean Baptiste Pierre Antoine de Monet de Lamarck.]