(evolutionary theory, historical) The theory that structural variations, characteristic of species and genera, are produced in animals and plants by the direct influence of physical environments, and especially, in the case of animals, by effort, or by use or disuse of certain organs.

A surname.

(biology, historical) Lamarckism as revived, modified, and expounded by later biologists, especially as maintaining that the offspring inherits traits acquired by the parent from change of environment, use or disuse of parts, etc.

Alternative form of Neo-Lamarckism