# Lamarckism

> English word · Noun · IPA /ləˈmɑːkɪzəm/

## Definitions
1. 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.

## Etymology
Internationalism, from Lamarck (i.e. its proponent Jean-Baptiste Lamarck) + -ism.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/lamarckism