/ Dictionary / Index L Lamarckian: Meaning and Definition of Find definitions for: La•marck•i•an Pronunciation: (lu-mär'kē-un), [key] — adj. of or pertaining to Jean de Lamarck or his theory of organic evolution. —n. a person who holds this theory. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: lamarckian (Thesaurus) Lamarck Lamarckism Related Content Daily Word Quiz: blithesome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language