"pertaining to the theories or work of French botanist and zoologist Jean-Baptiste Pierre Antoine de Monet de Lamarck" (1744-1829). Originally (1825) in reference to his biological classification system. He had the insight, before Darwin, that all plants and animals are descended from a common primitive life-form. But in his view the process of evolution included the inheritance of characteristics acquired by the organism by habit, effort, or environment. The word typically refers to this aspect of his theory, which was long maintained in some quarters but has since been rejected.