/ Dictionary / Index L Lagrange's theorem: Meaning and Definition of Find definitions for: Lagrange''s the"orem Pronunciation: [key] — Math. Math. the theorem that the order of each subgroup of a finite group is a factor of the order of the group. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Lagrange's method Lagrangian function Related Content Daily Word Quiz: lunar Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language