# Lagrange's theorem

> English word · Noun

## Definitions
1. The theorem in group theory that for any finite group, the size (order) of any subgroup must be a divisor of that of the group itself.

## Etymology
Named after Joseph Louis Lagrange (1736–1813), an Italian Enlightenment Era mathematician and astronomer.

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