lamarckism /ləmär″kizəm/ [Jean B.P. de Lamarck, French naturalist, 1744–1829; Gk, ismos, practice] , a theory postulating that organic evolution results from structural changes in plants and animals caused by adaptation to environmental conditions and that these acquired characteristics are transmitted to offspring. Also called Lamarck’s theory, lamarckianism. Compare darwinian theory. −lamarckian, adj., n.
